Technical Program

Status: 3 June, 2022
Tuesday, 31 May, 2022
08:30 - 10:20
Refractory Metals - Materials 2
Location: Walter Schwarzkopf Hall
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08:30 RM 6
Alloy Designs for High Temperature Mo-Base Systems - KEYNOTE
Perepezko J.1, Su R.1, Liu L.2
1University of Wisconsin-Madisonin-Madison, USA
2University of Wisconsin-Madison, USA
For high temperature applications Mo base alloy requirements include both superior structural performance and environmental resistance. To address these requirements alloys in the Mo-Si-B system and multi-principal element alloys (MPEA) are being developed that exhibit a promising potential, but also have some remaining challenges to improve ductility, lower density and enhance environmental resistance. In the Mo-Si-B system microstructures with a Mo solid solution (Moss) Mo3Si and Mo5SiB2 (T2) phases have been the focus of attention. However, the Si solubility in the Moss phase diminishes the ductility and toughness. In order to address this issue a new design based upon Moss , Mo2B and T2 phases lowers the Si solubility in the Moss to improve ductility while the T2 phase maintains the oxidation performance. Selected additions of Al and Ti enable a density reduction to 8.5 gm/cm3 or lower. The MPEA designs for Mo-rich alloys provide for excellent structural performance, but the complex oxidation products provide no protection. In this case a new coating design has been introduced that provides the required environmental resistance.
High Hardness and Strength W-Cu Composite with Hierarchical Nanostructure cancelled
Hou C.1, Lu H.1, Tang F.1, Song X.1
1Beijing University of Technology, China
Hierarchical nanostructured W-Cu composite was constructed taking advantage of additional intermediary component. The hierarchical configuration contains three orders of microstructure. The first-order microstructure is composed of refined micron scale W-based phase and Cu phase. The second-order structure within the W-based phase consists of W and Cu nanostructure. The third-order structure is dispersive nanoparticles containing intermediary component on the nanocrystalline W grains. The formation mechanism of the hierarchical nanostructure was investigated based on the adjustable thermodynamics stability of W-Cu system by intermediary component. Furthermore, the properties of typical interfaces, including energy and separation work, and underlying electronic mechanism were also disclosed through first-principles calculation. Due to a large number of heterogeneous interfaces, the hierarchical nanostructured W-Cu composite exhibits strong resistance against plastic deformation. Correspondingly, the hardness and compressive strength are 2 and 1.7 times as those of traditional coarse-grained W-Cu composites. This work will help to understand the important effect of composition on the microstructure and further to achieve high mechanical performance of immiscible W-Cu composite.
09:20 RM 8
Thermodynamic optimization of the Co-Ni-W system and alloy design applications
Bouliez N.1, Andrieux J.2, Chiriac R.2, Toche F.2, Gardiola B.2, Bigot J.-M.1, Charnay G.1, Cury R.1, Dezellus O.2
1Plansee Tungsten Alloys, France
2Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France
Tungsten Heavy Alloys (WHAs) require a combination of high strength, density and toughness for aerospace and defense applications. Their improvement calls for an accurate knowledge of phase equilibria in the Co–Ni–W system through a wide range of temperatures. WHAs are prone to embrittlement from interfacial precipitation of intermetallic phases.
Thermodynamic data regarding phase equilibria below 1000°C were recently provided by N. Bouliez et all. [1]. New characterizations to evaluate the liquid phase formation at high temperatures and diffusion multiples from pure Co, Fe, Ni and W were built to assess phase equilibria on a large composition range. All the data were considered to design a new CALPHAD modeling of the Co-Ni-W system. From this new thermodynamic description, the composition range for which intermetallic precipitation is avoided is extremely narrow. However, decomposition temperatures for the intermetallic phases are now available to set a temperature limit for industrial heat-treatments. As a consequence, the investigated alloys featured a controlled microstructure and were mechanically characterized to assess their potential for industrial applications.  
[1] N. Bouliez, J. Andrieux, R. Chiriac, F. Toche, J-C. Crivello, B. Gardiola, S. Cazottes, F. Robaut, R. Cury, O. Dezellus, Low temperature study of phase equilibria in the Co–Ni–W ternary system: Evidence of a new intermetallic phase Co3W-D0a, Journal of Alloys and Compounds, accepted september 2021.
09:40 RM 9
Defects formation in tungsten irradiated at various temperatures
Klimenkov M.1, Jäntsch U.1, Rieth M.1, Dürrschnabel M.1, Schneider H.-C.1
1Karlsruhe Institute of Technology (KIT), Germany
Due to its advantageous properties such as high melting point, high sputtering resistance and low coefficient of thermal expansion, tungsten is the prime candidate for construction of plasma-based components in future fusion reactors. During the operation of fusion reactors, neutron irradiation leads to the formation of structural defects such as dislocation loops and voids due to displacement damage. Additionally, the complex chain of transmutation reactions causes the formation of new elements such as rhenium and osmium, which form precipitates in tungsten. Irradiation of specimens was performed in the fuel channel of the material test high flux BR2 reactor (SCK-CEN, Mol, Belgien) at 600°C, 800°C, 900°, 1000°C, 1100°C and 1200°C up to an accumulated damage dose close to 1 dpa.
The materials were examined with a transmission electron microscope (TEM) to quantify the microstructural changes occurring due to irradiation. The investigations show the radiation-induced formation of voids with a size between 4 nm and 32 nm, dislocation loops and the precipitation of rhenium and osmium on voids and grain boundaries. The formation of rhenium-rich particles with globular and acicular shapes was only found at irradiation temperatures below 1100°C. Application of high resolution TEM analysis make it possible to identify σ-W(ReOs)2 and χ-W(ReOs)3 precipitates.
The defects lead to swelling, radiation hardening and embrittlement of tungsten, which can significantly limit the service life of components. Knowledge of this radiation damage is thus highly important for evaluating the service life of tungsten components.
10:00 RM 10
On the mechanism controlling the ductile-to-brittle transition in tungsten with room-temperature ductility
Bonnekoh C.1, Reiser J.1, Hartmaier A.2, Lied P.1, Hoffmann A.3, Rieth M.1
1Karlsruhe Institute of Technology, Germany
2Ruhr-University Bochum, Germany
3Plansee SE, Austria
Transition temperatures far below room temperature have raised questions about the mechanism that controls the ductile-to-brittle transition (BDT) in ultrafine-grained tungsten. Besides the glide of screw dislocations also a high density of non-screws and boundary-dislocation interactions are discussed in terms of dislocation dynamics.
To clarify this dissent, an attempt was made to identify the rate-limiting mechanism of plasticity by means of BDT Arrhenius activation energies. Campaigns of fracture toughness tests were conducted, whereby the loading rate was varied over five orders of magnitude. For the first time, we give evidence that the transition temperature in ultrafine-grained tungsten still follows an Arrhenius relationship, even well below room temperature. Parallel to the deformation-induced reduction of the transition temperature as reported in recent works, also the BDT Arrhenius activation energy is decreased by severe rolling. A comparison of the BDT Arrhenius activation energies and the expected values for kink-pair formation reveals a good correlation between both. This indicates that the glide of screw dislocations controls the dynamic of plastic deformation in ultrafine-grained tungsten.
10:20 - 10:40
Location: Walter Schwarzkopf Hall
10:40 - 12:20
Refractory Metals - Applications
Location: Walter Schwarzkopf Hall
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10:40 RM 11
The past informs the future: looking back on Refractory Metal applications over a 45 year career new
McCrossan S.1
11:00 RM 12
Impact of microstructure on the performance of WRe10 conversion layers for stationary and rotating anodes
Siller M.1, Bogust P.2, Bostrom N.2, Schatte J.1, Gerzoskovitz S.1, Pippan R.3, Clemens H.4, Maier-Kiener V.4
1Plansee SE, Austria
2Varex Imaging Corporation, USA
3Austrian Academy of Sciences, Austria
4Montanuniversität Leoben, Austria
The focal track of high-performance rotating anodes withstands extreme temperatures, thermal shock and thermal fatigue during the operation of X-ray tubes. Overloading the focal track manifests itself in undesired operational instabilities and reduced X-ray output of the X-ray tube.
In the present work a novel test system was developed to test stationary anodes, exhibiting WRe10 conversion layers with different microstructures, by means of pulsed electron beam loading. The samples were exposed to a maximum temperature of 2350°C and show comparable surface damage features compared to rotating anodes. The measured reduction in X-ray output with consistent filtration and a 100kV tube voltage was up to 35% due to target damage.
A columnar grain microstructure led to a significant increase in performance due to the early formation of stable and orientated crack networks. In contrast, Pancake-shaped grains stacked parallel to the surface caused local overheating due to the formation of cracks parallel to the surface and the resulting local thermal isolation.
11:20 RM 13
Oxidation-resistant tungsten-based alloys as plasma-facing materials in nuclear fusion reactors
García-Rosales C.1, Sal E.1, Hunger K.2, Schlüter K.2, Gago M.3, Wirtz M.3, de Prado J.4, Sánchez M.4
1Ceit-IK4 and University of Navarra, Spain
2Max-Planck-Institut für Plasmaphysik, Germany
3Forschungszentrum Jülich GmbH, Germany
4Universidad Rey Juan Carlos, Spain
Tungsten is the candidate material for the first wall armour of nuclear fusion reactors. However, the poor oxidation resistance of tungsten represents a risk in case of a loss-of-coolant accident with simultaneous air ingress, where volatile and radioactive tungsten oxides could be formed. A way for producing oxidation-resistant tungsten-based alloys is the addition of oxide-forming elements to tungsten leading to formation of a passivating layer at high temperatures.
This paper summarizes the work on W-Cr-Y and W-Cr-Y-Zr alloys manufactured by mechanical alloying followed by HIP and subsequent heat treatment, where an ultrafine-grained, single bcc phase, fully dense microstructure is obtained. Isothermal oxidation tests reveal a reduction of oxidation rate at 1000°C three orders of magnitude lower than pure tungsten. W-Cr-Y-Zr exhibits an improved thermal shock resistance compared to pure tungsten, with no damage after 1000 pulses of 0.38 GW/m2 power density and 1 ms duration. The single-phase microstructure remains unchanged after 3000 h at 650°C. Joining of W-Cr-Y to steel by diffusion bonding via HIP results in a shear strength significantly higher than pure tungsten.
11:40 RM 14
The effect of different seed layers on the resistivity of Molybdenum thin films
Köstenbauer H.1, Linke C.1, Lorenz D.1, Schmidt H.2, Winkler J.1
1Plansee SE, Austria
2Plansee (Shanghai), China
Molybdenum gate line resistance is a critical item for future high end TFT devices. Despite the long-standing usage and well-known process integration of Mo some applications e.g. high-resolution displays, might require even lower resistance metal lines in the future. Depending on process parameter and equipment used, sputtered Mo films typically yield resistivities around 11.0 µΩcm. The positive effect on film conductivity of a TiW seed layer below a Mo layer was reported in literature 20 years ago. In our work we used different Mo alloys, W and Ti as seedlayer below a 300nm thick Mo layer which results in up to 30% improvement in film conductivity in the best case. It is shown that the seedlayer significantly changes the texture and domain size of the growing Molybdenum film depending on seedlayer material. Good process integration is proven by dry etching tests for the most promising seedlayer materials.
12:00 RM 15
In situ generated biocides by transition metal oxides exhibit strong antimicrobial activity on surfaces
Guggenbichler J.P.1
1AMiSTec GmbH & Co. KG, Austria
A dramatic increase of microorganisms resistant against antibiotics and disinfectants has been reported. It has now been identified by major world health organizations as one of the global top health challenges facing the 21st century. There is an urgent need for prevention of infections and to stop the spread of these multi resistant microorganisms.

Transition metal oxides (Lewis acids) e.g. MoO3, Tungsten blue oxide and Zinc Molybdate are embedded into polymers, paints and coatings and  work as in situ generated biocides. Acidified water molecules are formed from ambient humidity by electron transfer from transition metal oxides. Also free radicals e.g. oxygen radicals and hydroxyl ions are formed. Last not least a positive Zeta potential attracts  electronegative charged microorganisms - the phospholipid bilayer of microorganisms is disrupted within minutes. There is a 8 log 10 reduction of microorganisms on a surface in less than 1 hour:

This technology provides antimicrobial activity against a very broad range of  micro-organsms including Gram-positive and Gram-negative microorganisms, fungi and many viral pathogens including COVID 19.
Various transition metal oxides e.g. Molybdenum oxide, oxygen deficient tungsten blue oxide, Zinc molybdate and polyoxometallates where Molybdenum oxides are incurporated into the  tungsten blue crystal lattice function as catalysts. The latter shows a particularly strong Zeta potential with activity against molds, algae and many viral pathogen e.g. hepatitis B, C and Coronavirus.  The antimicrobial activity lasts  for a minimum of 10 years. The technology is approved by the biocidal product regulation.
12:20 - 13:00
Lunch Break
Location: Walter Schwarzkopf Hall
13:00 - 14:20
Hard Materials - Applications
Location: Walter Schwarzkopf Hall
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13:00 HM 6
Onset of damage in WC-Co hard metal milling tool cutting edges as a function of cyclic load amplitude, temperature and microstructure
Klünsner T.1, Maier K.1, Kaltenbrunner T.1, Ecker W.1, Pichler P.1, Marsoner S.1, Krückl H.-P.1, Wosik J.1, Teppernegg T.2, Czettl C.2
1Materials Center Leoben Forschung GmbH (MCL), Austria
2CERATIZIT Austria GmbH, Austria
Today the understanding of the conditions for the onset of damage in milling tools made of WC-Co hard metals is incomplete. To improve this understanding, the stresses and temperatures acting locally at a milling tool’s cutting edge were studied via finite element modelling. The associated damage evolution in real-world milling tools was investigated via scanning electron microscopy in cross-sections prepared by focused ion beam milling. Sub-surface nm-sized pores were recognized to form, which merged to µm-sized cavities and finally even larger cracks that lead to the rise of breakouts at the cutting edge. The same type of damage observed in the milling tools was also detected in laboratory specimens subjected to uniaxial cyclic high-temperature loads in an amplitude range determined in the tool load simulations. Limits of cyclic high-temperature load for the onset of material damage were described systematically as a function of hard metal microstructure and temperature. In that manner, the onset conditions for sub-surface damage in milling tools and therefore limits of save tool operation were described quantitatively for the first time.
13:20 HM 7
Face-Milling of Aerospace Grade 7075 Aluminium Alloy Using Laser Surface Modified WC and NbC Based Cemented Carbides with Mo2C and TiC Additions
Nhema K.1, Mphasha N.2, Genga R.3, Huang S.4, Vleugels J.4, Zeman P.5, Nelwalani N.6, Janse van Vuuren A.7, Polese C.8
1School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand, South Africa
2School of Chemical and Metallurgical Engineering, University of the Witwatersrand, South Africa
3School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand; Academic Development Unit (ADU), University of the Witwatersrand; DSI-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, South Africa
4Department of Materials Engineering (MTM), KU Leuven, Belgium
5Department of Production Machines and Equipment (RCMT), Faculty of Mechanical Engineering, Czech Technical University in Prague, Czech Republic
6School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, South Africa
7CHRTEM, Nelson Mandela University, South Africa
8School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand; DSI-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, South Africa
The effects of rapid sintering (PECS), Mo2C and TiC grain growth inhibitor additions and laser surface modification (LSM) on the microstructure, mechanical properties, and tool life during dry face-milling of aerospace grade 7075 aluminium alloy using WC and NbC based cutting inserts were investigated. LSM was done to improve the abrasion, attrition, and thermal wear resistance. Face-milling was conducted at cutting speeds (vc) ranging from 100 – 600 m/min, depths of cut (ap) from 0.5 – 2.0 mm, and 20 min cutting time. Insert wear was analysed by optical microscopy, scanning electron microscopy (SEM) and annular dark field (ADF) imaging in scanning transmission electron microscopy (STEM). Generally, the WC based inserts had better tool lives than NbC based inserts during roughing, semi-finishing and finishing tests. LSM improved tool life of liquid phase sintered inserts during semi-finishing and finishing, reducing VBmax (maximum flank wear) of WC-Cr2C3-Co and NbC-TiC-Ni inserts from 214 to 156 μm/min and 249 to 190 μm/min, respectively. During finishing, LSM improved the tool lives of LPS WC-TiC-Mo2C-Co and NbC-TiC-Ni inserts with > 20%.
13:40 HM 8
Development of WC-NiCrMo hardmetals
Pereira P.1, Ferro Rocha A.M.2, Bastos A.C.2, Oliveira F.J.2, Vilhena L.M.3, Ramalho A.3, Sacramento J.1, Malheiros L.F.4, Senos A.M.R.2
1DURIT - Metalurgia Portuguesa do Tungsténio, Lda, Portugal
2University of Aveiro, Department of Materials and Ceramic Engineering/ CICECO, Portugal
3CEMMPRE – Centre for Mechanical Engineering, Materials and Processes, University of Coimbra, Portugal
4Faculty of Engineering of the University of Porto, Portugal
The demand for improved carbide components with a wide range of properties is a reality in today’s market. Furthermore, supply shortages of raw materials such as Co have resulted in price increases and fluctuations. Together with environmental and health issues, promote the demand for alternative or modified binders. Therefore, in this work, WC-NiCrMo composites were developed as a potential alternative to conventional WC-Co hardmetals. In order to evaluate this new hardmetal composite, prototypes of submicrometric WC-NiCrMo (~15vol.%) were produced by conventional powder metallurgy route. Thermodynamic assessment, wettability testing, and constant heating rate dilatometry were performed to an adequate sintering route. A detailed characterization of its mechanical properties (Young’s modulus, Vickers hardness, and fracture toughness), together with corrosion (OCP, polarization curves, EIS) and abrasive wear (ball-cratering) resistance evaluation, were undertaken. Good wettability of melted NiCrMo binder on WC surface was observed, and highly dense compacts could be successfully attained by gas pressure sintering. Higher corrosion and better wear resistance of WC-NiCrMo composite compared to conventional WC-Co was observed, while maintaining a good level of mechanical properties.
14:00 HM 9
Tuned mass dampers for boring bars with small diameter
Hintze W.1, Hinrichs M.1, Rosenthal O.1, Schleinkofer U.2, Venturini R.2
1Hamburg University of Technology, Germany
2CERATIZIT Austria GmbH, Austria
Universal turning tools should be able to suppress chatter in a wide range of cutting conditions.  Especially in operations using boring bars, chatter with various effective directions arises mainly from the regenerative effect or the falling cutting force characteristic of the cutting processes. The common approach to avoid chatter by reducing the depth of cut or adjusting the spindle speed is not applicable in finishing with such tools since the depth of cut is usually smaller than the corner radius and the stability lobe diagram shows no distinct maxima at suitable cutting speeds. Tuned mass dampers (TMD) are a common method to reduce self-excited vibrations. However, for boring bars with smaller diameters the design space to realize a TMD is restricted. A novel TMD consisting of a mass and a spring-damper combination is integrated into to the front end of such tools with small diameter. The tool design based on dynamic modeling and simulations has proven its superior performance during cutting tests regarding stability and surface quality.
14:20 - 14:50
Location: Walter Schwarzkopf Hall
14:50 - 16:30
Hard Materials - PVD Coatings
Location: Walter Schwarzkopf Hall
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14:50 HM 11
Influence of self-lubricating tool coatings on cutting temperature and coefficient of friction during turning of Ti6Al4V
Hintze W.1, Möller C.1, Ploog P.1, Bobzin K.2, Kalscheuer C.2, Carlet M.2, Stachowski N.2
1Hamburg University of Technology, Germany
2RWTH Aachen University, Germany
The use of titanium alloys such as Ti6Al4V contributes significantly to performance improvements in various industry sectors. However, machining of titanium alloys is a considerable challenge due to low thermal conductivity and Young’s modulus as well as the strong tendency to adhesion. These lead to high thermal and mechanical loads on the cutting edge resulting in early tool failure.
CrAlVN coatings are a promising approach to reduce these effects as they form self-lubricating oxide phases under tribological loads during turning.
The influence of a self-lubricating CrAlVN coating based on the specific transition metal vanadium on the cutting temperature and the friction coefficient is investigated. Turning tests using coated and uncoated tools at variable feed rates and cutting speeds were carried out in which the temperature on the rake face was measured using a high-resolution two-colour pyrometer. Furthermore, cutting forces are measured and subsequently coefficients of friction are evaluated. These results are then compared with thermo-chemical annealing tests and pin-on-disk investigations of the coating against Ti6Al4V.
15:10 HM 12
Combinatorial application of advanced high resolution characterization methods for the investigation of the microstructure of ZrN/Ti(Al)N multilayer coatings
Frank F.1, Schalk N.1, Waldl H.1, Todt J.2, Keckes J.2, Letofsky-Papst I.3, Czettl C.4, Pohler M.4, Tkadletz M.2
1Christian Doppler Laboratory for Advanced Coated Cutting Tools at the Department of Materials Science, Montanuniversität Leoben, Austria
2Department of Materials Science, Montanuniversität, Austria
3Institute for Electron Microscopy and Nanoanalysis and Center for Electron Microscopy, Graz University of Technology, Austria
4CERATIZIT Austria GmbH, Austria
In order to develop efficient protective hard coatings for cutting applications, detailed knowledge about their microstructure is crucial. Conventional methods for the characterization of the microstructure e.g. X-ray diffraction and scanning electron microscopy are well established. However, the characterization of coatings with a graded or multilayer architecture demands more sophisticated approaches. Synchrotron X-ray nanodiffraction enables the evaluation of gradients in phase composition, strain and texture with a local resolution <30 nm, while atom probe tomography and transmission electron microscopy allow to gain insight into microstructural features close to atomic resolution. Within this work, the potential of the complementary application of these methods is shown, illuminating the microstructure, elemental and phase distribution and interface properties of cathodic arc evaporated ZrN/Ti(Al)N multilayer coatings with a bilayer thickness on the nanometer scale.
15:30 HM 13
Properties and phase stability of hard multicomponent (HfNbTiVZr)C thin films
Osinger B.1, Fritze S.1, Riekehr L.1, Lewin E.1, Jansson U.1
1Uppsala University, Sweden
Thin films of the high entropy alloy HfNbTiVZr have shown promising mechanical properties and interesting charge transfer effects, reducing atomic size mismatch and in turn the lattice distortion δ. Being able to tune the electronic structure is especially interesting for the design of multicomponent carbides, as their desirable properties are a result of their bond character. This, along with general properties of group 4-6 carbides, like ceramic hardness, high wear resistance and ultra-high temperature strength, motivates the investigation of the (HfNbTiVZr)C system.

This study focused primarily on multicomponent carbide (HfNbTiVZr)C thin films with varying carbon concentrations (0 44 at.%), synthesised by non-reactive DC magnetron sputtering. All carbide films exhibit a single solid solution phase with NaCl-type structure and a lattice parameter of approximately 4.53 Å. The hardness increases to 34 GPa compared 10 GPa for the metallic films. Additionally, phase stability, based on films deposited at elevated temperatures (300-700°C), compared with predictions made by CALPHAD methods, are discussed.
15:50 HM 14
Superlattice effect on the mechanical properties of transition metal diboride coatings
Hahn R.1, Tymoszuk A.A.1, Hunold O.2, Polcik P.3, Mayrhofer P.H.4, Riedl H.1
1Christian Doppler Laboratory for Surface Engineering of high-performance Components, TU Wien, Austria
2Oerlikon Balzers, Oerlikon Surface Solutions AG, Liechtenstein
3Plansee Composite Materials GmbH, Germany
4Institute of Materials Science and Technology, TU Wien, Austria
PVD deposited superlattice structures enable the simultaneous enhancement of hardness and fracture toughness of thin ceramic coatings – evading the strength-ductility trade-off dilemma. While a deeper understanding of this effect has been gained for transition metal nitrides, hardly any knowledge is yet available for diborides. Here we show that superlattices can—similarly to nitrides—increase both mechanical properties of diboride coatings. For this purpose, we non-reactively deposited the systems TiB2/WB2 and TiB2/ZrB2, the former is characterized by a high difference in shear modulus, the latter features a high lattice mismatch of the participating layer materials. By applying nanoindentation as well as in-situ microcantilever bending tests, we show that TiB2/WB2 exhibits a distinct increase in hardness (up to 45.5 ± 1.3 GPa), while we could not observe an increase in KIC. Vice versa, TiB2/ZrB2 shows no increase in H, while KIC increases by ~ 20% up to 3.70 ± 0.26 MPa∙m1/2. These results are discussed using further analytic methods, such as X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM), and are complemented by an extensive literature review.
16:10 HM 15
Analysis of the micromechanical behaviour of PVD coatings and substrate materials to predict machining and cutting behaviour
Frank H.1, Joost H.1, Schiffler M.1
1GFE - society of production engineering Schmalkalden, Germany
Significant aspects of wear when cutting difficult to machine materials, such as tool chippings, crater and flank wear or delamination, significantly influenced by tribological and micromechanical effects. These are influenced by the mechanical and thermal properties of coatings and tools as well as the process conditions. The correlation between tribological and micromechanical effects and wear is usually determined by analysing coating and surface properties (e.g. hardness, roughness, residual stresses) or basic wear tests. These analyses can give limited information about the operational behaviour.
In the contribution, various options for tribological analysis are explained. A new process is the micro-impact process, in which a dynamic cyclic load is applied. The micro-impact test enables the evaluation of the micromechanical behaviour (e.g. fatigue, crack formation). Using the results, wear and failure mechanisms then can estimated. These allow a derivation of possibilities for improving the coating and surface properties, for example to increase the coating adhesion or to reduce the formation of cracks. The applicability of the micro-impact process is shown using different PVD coating concepts (Arc, Sputtering).
16:30 - 17:00
Location: Walter Schwarzkopf Hall
17:00 - 20:00
Poster Session Hard Materials - Simulation and material design
Location: Poster Hall I
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HM 136
Evolution of a γ/γ′ microstructure and appearance of a κ-phase in the WC/Co-Ni-Al-W system as a function of carbon
Edtmaier C.1, de Oro Calderon R.1, Wolf M.1, Steinlechner R.1
1TU Wien, Austria
Modifications of the binder phase (γ) of cemented carbides by (partially) coherent precipitations with L12 structure (γ’) have the potential to increase hardness and wear resistance without sacrificing tensile strength or toughness. γ’ is a metastable phase in the Al-Co-W ternary system in the form of Co3(Al,W) which is stabilized by the substitution of cobalt with nickel. Superalloys of the composition Co-xNi-11Al-9W and Co-xNi-9Al-7W with different nickel and carbon contents were prepared by inductive melting and the resulting microstructures were analysed by SEM-EDS, XRD and Vickers hardness. Cemented carbides from the same superalloy compositions with resulting γ/γ’ binder microstructure were prepared via DTA. It was shown that nickel stabilizes the γ’ phase in superalloys as well as in cemented carbides. Carbon leads to the formation of an additional phase with E21 structure (κ) depending on the carbon content.
HM 137
Performance enhancement of ultra-coarse cemented carbide by WCoB addition
Liu X.1, Song X.1, Hu H.1
1Beijing University of Technology, China
Ultra-coarse WC-Co cemented carbide whose mean grain size is greater than 5 μm is an irreplaceable material of key tools in mining industries and constructions. Served under complex impacting load and wear conditions, the cemented carbide typically exhibits failure mechanisms of brittle fracture and excessive wear. To achieve enhanced mechanical performance, ultra-coarse cemented carbide with WCoB addition was prepared. The effects of WCoB addition on the microstructure, mechanical properties and wear behavior of the prepared cemented carbides were studied, and the mechanisms of the performance enhancement were analyzed by experiments and finite element simulations. The results show that WCoB addition has only slight influence on the grain size, but is beneficial for the comprehensive properties and wear resistance of the ultra-coarse cemented carbides at all tested temperatures. The reason is that WCoB has higher hardness than WC and forms WCoB/WC and WCoB/Co interfaces with high bonding strength. Moreover, WCoB can reduce oxidation at high temperatures and protect WC grains from fragmentation and pullout after Co removal, which leads to the increased wear resistance of WCoB containing cemented carbide at all temperatures.
HM 139
Development of new ultrafine cemented carbide by WC-Ti(C,N)-Cr3C2-Co alloy
Takada M.1, Tsutsumi T.1, Mori Y.1, Matsubara H.2
1Nippon Tokushu Goukin, Co. Ltd., Japan
2Dept. Environment Studies, Tohoku University, Japan
WC-Co ultrafine cemented carbides with different particle sizes of Ti(C,N) were prepared by liquid phase sintering. The microstructure of these alloys was investigated by comparing with the microstructure of alloys with VC and Cr3C2.  The larger the amount of Ti(C,N) added and the smaller the particle size of Ti(C,N), the stronger the inhibition of the grain growth of WC particles. From the relationship of the particle sizes of WC and the Ti(C,N), it was found that the mechanism of the grain growth inhibition effect by adding Ti(C,N) particles was the pinning effect (Zener) of the second phase particles, which was considered to be different from the conventionally reported mechanism of addition of VC and Cr3C2. The combined addition of Cr3C2 to this alloy resulted in extremely high strength, with the average transverse-rupture strength of 4.7 GPa and the maximum strength of 5.1 GPa, the world’s highest level. When these materials were applied to a cutting tool, it showed excellent cutting life.
17:00 - 20:00
Poster Session Hard Materials - Chemical vapor deposition
Location: Poster Hall I
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HM 72
Cold Spray Additive Manufacturing (CSAM) of coatings with high densities and low porosities
Brotsack M.1
1Impact Innovations GmbH, Germany
Cold Spray a technology invented by accident, with applications used in kitchens and to reach out into space. This wide range of applications is possible because of the highly flexible, fast and efficient technology. Cold Spray does neither fuse nor melt the sprayed metal powders onto substrates, in contrast to conventional thermal spray processes. Therefore thermal influences are minimal during this process and due to that there are no changes to grain size distribution or oxidation level to the sprayed metals, a huge advantage for applications demanding corrosion resistance. Because of only using kinetic energy to build layer by layer this additive manufactruing technology is able to work with ductile metals like Copper or Silver, but on the other hand side also refractory metals, like Niobium, Tantalum or Zirconium. Examples will be presented, like electromagnetic coatings on pans, wear resistant coatings for roles, coatings for thermal management for different electrical applications, different implemenations for repair task in aviation industry and finally the manufacturing of parts for space industry, like combustion chambers or rocket nozzles.
HM 73
Structure and Properties of nanostructured ZrTiAlN coatings exhibiting exceptional performance in milling of Ti-6Al-4V
Shaha K.1, Rapp O.1
1Ceratizit Balzheim GmbH and Co. KG, Germany
Titanium alloys are difficult-to-machine materials by virtue of their high chemical reactivity, low thermal conductivity, high strength, and high work hardening rate. Application of coating on the tool surface is widely employed to reduce wear and improve the tool life during machining of these materials. Nano-/multilayer coatings comprising combination of materials in the form alternate layers have attained increasing interest due to the added degree of freedom in tailoring the coating properties. The composition and thickness of individual layers, number of interfaces, and crystallographic relations between the layers mainly characterize the properties of multilayer coatings. In this work, nanostructured multilayer ZrTiAlN coatings
deposited on Solid carbide End Mills by cathodic arc evaporation, and their crystal structure, mechanical properties as well as wear behaviour, and tool life in milling of Ti-6Al-4V alloy are presented. The coatings were characterized by XRD, EBSD, HRSEM, EDX, and Nano-indentation. It is shown that a significant increase in tool life can be achieved by tuning the microstructure of these coatings.
HM 74
Development of Early Transition Metal Carbide Superlattices via Compound Target Magnetron Sputtering
Schmid B.1, Koutná N.1, Buchinger J.1, Hahn R.1, Moraes V.1, Pitthan E.2, Primetzhofer D.2, Mayrhofer P.H.1
1Vienna University Of Technology, Austria
2Uppsala University, Sweden
Transition metal carbides are known to feature high thermal and mechanic stability as well as high melting points, sometimes above 4000 °C, and can be regarded as ultra-high temperature ceramics (UHTC). The huge downsides to those materials is their noticable inherent brittleness.
Superlattice architecture describes the alternation of coherently grown nanolayers of two or more materials. By creating such superlattices, optical, magnetic, electronic, tribological or mechanical properties can be influenced. The hardness but also the toughness of superlattice materials can be significantly higher than their monolithic components.
Therefore, we developed superlattice structures of some selected transition metal carbide materials such as ZrC and HfC to prove if this is applicable in this case.
The selection of carbide combinations is based on density functional theory simulations, which revealed them as most promising candidates to have an improved toughness behavior due to the superlattice structure.  
All coatings are developed via DC magnetron sputtering using the respective ceramic targets. Their characterization includes scanning SEM, EDX and ERDA analysis, XRD, nanoindentation, and fracture toughness testing (via in-situ micromechanics).
HM 75
Durability of hard protective coatings: Insights on fracture and fatigue mechanisms
Zauner L.1, Hahn R.1, Hunold O.2, Polcik P.3, Riedl H.4
1TU Wien - Christian Doppler Laboratory for Surface Engineering of high-performance Components, Austria
2Oerlikon Balzers, Oerlikon Surface Solutions AG, Liechtenstein
3Plansee Composite Materials GmbH, Germany
4TU Wien - Christian Doppler Laboratory for Surface Engineering of high-performance Components, TU Wien - Institute of Materials Science and Technology, Austria
Tailoring the intrinsic fracture characteristics of hard protective coatings towards fatigue properties of state-of-the-art bulk materials is paramount for the application of innovative coating materials extending the fatigue-life of high-performance components. Thus, an in-depth knowledge on the failure pathways of ceramic-based thin films – typically lacking in intrinsic ductility – but also coated components under cyclic loading is imperative to extend their lifetime. Here, we present a novel approach using quasi-static and cyclic bending of pre-notched, unstrained micro-cantilever beams in conjunction with in-situ synchrotron X-ray diffraction to reveal the intrinsic fracture toughness and critical failure aspects of thin films under various loading conditions. Up to the high-cycle fatigue regime (i.e., N=10^7 cycles), the failure of monolithic coatings is shown to be dominated by the inherent fracture resistance, irrespective of the bonding character. The observed fracture behaviour is further correlated with large-scale dynamic-mechanical analysis of coated Ti6Al4V platelets to include residual stress states and the coating-substrate interface. The results are expected to provide key-insights into the underlying mechanisms promoting crack growth in PVD coated specimens.
HM 76
12 µm coatings with HiPIMS
Schiffers C.1, Toni L.1, Hammer C.1
1CemeCon AG, Germany
The unique feature of HiPIMS is the ability to actively design the intrinsic stresses in a coating material. In-depth plasma analysis shows that the short HiPIMS pulses consist of several phases. Synchronizing the HiPIMS pulses on the cathodes with a pulsed Bias is the technique for attracting the ionized target species and forming the coating out of them while suppressing unwanted contributions such as gas ions.
Having control over the intrinsic stresses of a coating material by the timing of the HiPIMS synchronisation adds a fully new option to the coating designer’s toolbox: stress management of the material. This triggers a paradigm shift: hardness by the composition of the material and a dense, low stress coating morphology by the HiPIMS process.
Managing intrinsic stresses in HiPIMS gives new coating options such as 12 µm thick films for heavy duty insert milling applications as well as precisely defined stresses for making TiSiN coatings on micro-tools even ore wear resistant. Managing stresses in HiPIMS is about mastering stress and strain for the coating’s application.
HM 77
Development of microstructure defects in CVD Ti(C,N)/Al2O3 coatings
Ullrich C.1, Wüstefeld C.1, Šíma M.2, Pikner J.2, Rafaja D.1
1TU Bergakademie Freiberg, Germany
2Dormer Pramet, 787 53 Šumperk, Czech Republic
The Ti(C,N) base layers, which are intended as a mechanical support in hard CVD Ti(C,N)/Al2O3 coating stacks used for metal cutting applications, can be grown with a specific microstructure, which means in many cases desired preferred orientation of crystallites and defined grain size. These microstructure characteristics are typically controlled by the parameters of the deposition process. In our study, we investigated the formation of microstructure defects in fine-grained fcc-Ti(C,N) coatings having the preferred orientation {211}. During the subsequent deposition of Al2O3, the microstructure defects in Ti(C,N) partially undergo recovery processes. Based on the XRD and SEM/EBSD experiments, the microstructure of the Ti(C,N) layers was described in terms of the grain size, residual stresses, microstrains, global texture and mutual orientation of neighbouring crystallites, and correlated with the hardness of the coatings. The interplay between the defect density and the degree of the preferred orientation of crystallites obtained from XRD and EBSD is discussed.
HM 78
Microstructure, mechanical properties and thermal stability of arc evaporated Cr0.69Ta0.20B0.11N coatings
Kainz C.1, Pohler M.2, Tkadletz M.3, Czettl C.2, Schalk N.1
1Christian Doppler Laboratory Advanced Coated Cutting Tools at the Department of Materials Science, Montanuniversität Leoben, Austria
2Ceratizit Austria GmbH, Austria
3Department of Materials Science, Montanuniversität Leoben, Austria
While CrTaN coatings have recently gained increasing industrial interest due to their high hardness and good thermal stability, studies on quaternary CrTaBN are lacking in literature regardless of the promising effect of B on transition metal nitride coatings. Thus, the present work focusses on the microstructure, mechanical properties and thermal stability of Cr0.69Ta0.20B0.11N coatings grown by cathodic arc evaporation at varying bias voltages. All coatings crystallize in an fcc-CrxTa1-xN solid solution without indication for additional crystalline B containing phases. Increasing the applied bias voltage results in higher compressive residual stress and improved hardness. CrTaBN coating powders exhibit an excellent thermal stability, since the decomposition of the fcc-CrxTa1-xN solid solution into h-Cr2N and h-Ta5N4 only starts at ~1200 °C. After annealing the coatings on cemented carbide at 1200 °C, a reaction between the coating and the substrate induces the formation of fcc-TaC and bcc-Cr, which deteriorates the mechanical properties. The presented results confirm the beneficial effect of B alloying to CrTaN coatings and show the high potential of this material for use in metal cutting applications.
HM 79
Thermodynamic calculations and computational fluid dynamics (CFD) simulations of CVD process for AlTiSiN hard coating
Wang S.1, Du Y.2, Qiu L.3, Wang Y.1
1Shijiazhuang Tiedao University, China
2Central South University, China
3Ganzhou Achteck Tool Technology Co,. Ltd., China
In the present work, the effect of temperature, pressure and gas flow on the chemical compositions, phase assemblages and deposition rates of CVD-AlTiSiN coatings is investigated by integrating thermodynamic calculations and computational fluid dynamics (CFD) simulations with key experiments. The thermodynamic calculations predict that the Al contents of the films increase with increasing temperature under constant mixed gases and pressure. Under high SiCl4/AlCl3 gas flow ratio, AlN phase hardly occur. CFD simulations indicate that the coating deposition rate decreases with increasing distance to the gas pipe for the hard metal samples loaded on the same tray. Besides, higher rotation speed of the gas pipe has unfavorable effect on coating uniformity. Subsequently, AlTiSiN coatings were deposited by LPCVD method to verify the calculated chemical compositions and deposition rates. The experimentally measured results are in reasonable agreement with the theoretical predictions.
HM 80
Influence of the pressure on microstructure and mechanical properties of CVD TiAlSiN coatings
Wu L.1, Qiu L.2, Du Y.1, Zeng F.1
1Central South University, China
2Ganzhou Achteck Tool Technology Co., Ltd, China
TiAlSiN coatings were deposited on cemented carbide substrates by the low pressure chemical vapor deposition (LPCVD) method. The effect of total pressure on the microstructure and hardness of TiAlSiN coatings was studied in detail by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), and nanoindenter instrument. The results show that pressure has a great influence on the microstructure and mechanical properties of TiAlSiN coatings: under low pressure (800 Pa), the coating has a columnar crystal structure with a hardness of 28.4 ± 0.9 GPa; under a pressure of 6000 Pa, the formation of a featureless structure was observed in the TiAlSiN top-layer and the hardness reached to 31.7 ± 1.4 GPa. TEM results indicated that both CVD TiAlSiN coatings consisted of nanocrystalline embedded in SiNx amorphous.
HM 81
Microstructual characterization of textured CVD TiCN/TIAlN coatings
Ben Hassine M.1, Bäcke O.1, Stiens D.2, Manns T.2, Janssen W.2, Kummel J.2, Andren H.-O.1, Halvarsson M.1
1Chalmers University of Technology, Sweden
2Walter AG, Germany
In this work, two CVD coatings, one consisting of a TiCN layer deposited upon a Ti1-xAlxN layer, x>0.8, and the other consisting of the inverse configuration, have been grown on cemented carbide substrates pre-coated with TiN to understand how the underlying layer influences the growth of the upper layer. The deposition parameters where chosen so that the TiCN layer obtained a {211} texture and the TiAlN layer a {111} texture when deposited on TiN. Different electron microscopy and spectroscopy techniques were used to examine the structure and chemical composition of the two coatings at different scales, including grain size, texture and atomic configurations. The presence of interfacial dislocations, twins, stacking faults were revealed as well as the formation of new interfacial phases. It was found that the underlying layer overrides the texture driven by the process, giving the TiCN/TiAlN coating a {211} texture and the TiAlN/TiCN coating a {111} texture. However, the effect was found to be much more stable in the first case compared to the second.
HM 82
Thermal stability and phase transformations in CVD TiAlN coatings
Bäcke O.1, Qiu R.1, Stiens D.2, Manns T.2, Gardecka A.2, Janssen W.2, Kümmel J.2, Hörnqvist Colliander M.1, Halvarsson M.1
1Chalmers University of Technology, Sweden
2Walter AG, Germany
Phase separation of TiAlN and formation of cubic TiN and wurtzite h-AlN in CVD TiAlN coatings have been investigated in this work. TiAlN coatings with a high Al content, Ti(1-x) AlxN x>0.8, were annealed in argon for three hours at temperatures between 800°C and 1000°C and the degradation the coatings underwent was investigated using a combination of high resolution electron microscopy, energy dispersive X-ray spectroscopy and X-ray nanodiffraction. It was found that the TiAlN grains in the coatings are built up of a nanolamella structure, stemming from differences in the Ti/Al ratio, that coarsens with increasing annealing temperature before being transformed to TiN and h-AlN, inheriting the orientation of the TiAlN phase. The amount of TiN and h-AlN formed in the coatings increases with temperature and the transformation initiates along grain boundaries and the surface of the coatings. However, transformation along the former rapidly slows down with increasing temperature due to lack of free volume and most of the transformation is due to a transformation front sweeping down through the coatings from the surface.
HM 83
Deposition of CVD coatings using high reactivity gases
Traxler M.1, Lessiak M.1, Pitonak R.1, Weissenbacher R.1, Todt J.2, Keckes J.2, Zalesak J.2
1boehlerit GmbH & Co KG, Austria
2Montanuniversität Leoben, Austria
The common way to deposit hard protective coatings for metal machining is either physical or chemical vapour deposition (PVD or CVD). CVD coatings like Al2O3 are deposited at temperatures higher than 1000 °C. The usage of coatings, which are deposited at lower temperature, is often favoured due to shorter cycle times and lower costs. AlTiN for example can be produced at temperatures below 950 °C due to a higher reactivity of the gaseous reaction media. This strategy is also interesting for other coating systems like TiN and TiCN. In this contribution, results of these variations shall be discussed on the bases of the data from electron microscopy and X-ray diffraction in order to correlate structural properties with the performance of the particular coatings under special milling conditions.
HM 84
Influence of interplay of substrate template effects and bias voltage on the microstructure of cathodic arc evaporated fcc-Ti0.5Al0.5N coatings
Tkadletz M.1, Schalk N.1, Waldl H.1, Sartory B.2, Wosik J.2, Czettl C.3, Pohler M.3
1Montanuniversität Leoben, Austria
2Materials Center Leoben Forschung GmbH, Austria
3CERATIZIT Austria GmbH, Austria
Ever since the implementation of hard coatings as wear protection for cutting tools, their microstructural design has been of major interest. While the effect of the deposition parameters, such as the applied bias voltage, on the microstructure are frequently investigated and rather well understood, commonly less attention is paid to the used cemented carbide substrates. Yet properties like their phase composition and carbide grain size significantly influence the resulting coating microstructure. Thus, within this work substrate template effects are studied on fcc-Ti0.5Al0.5N coatings grown by cathodic arc evaporation onto cemented carbide substrates with different WC grain sizes. A systematic variation of the bias voltage, resulted in coarse, intermediate and fine grained coating microstructures, which revealed substrate template-based coating growth at low bias voltages and bias dominated coating growth at high bias voltages. The obtained results provide the basis to implement tailored microstructures with designed gradients of crystallite size and preferred orientation, which, as required, either utilize substrate template effects or avoid them.
HM 85
Thermo-mechanical properties of sputter deposited TMSi2 coatings (TM = Mo, Ta, Nb)
Bahr A.1, Richter S.1, Glechner T.1, Wojcik T.1, Ramm J.2, Hunold O.2, Kolozsvári S.3, Riedl H.1
1Christian Doppler Laboratory for Surface Engineering of high-performance Components, TU Wien, Austria
2Oerlikon Balzers, Oerlikon Surface Solutions AG, Liechtenstein
3Plansee Composite Materials GmbH, Germany
Future developments in the field of protective coatings to enhance the durability of high-performance components used in aerospace or energy industry are highly desired. High temperature environments not only involve materials with excellent creep properties, but also highest oxidation resistance and chemical inertness. Transition-metal (TM) disilicide based thin films are suggested as promising candidates for novel protective coating materials used in various high temperature applications. TMSi2 exhibit an attractive mix of highest phase stability, reasonable mechanical properties, and outstanding oxidation resistance.
Here, we investigated the role of Si on the phase formation and oxidation kinetics of sputter deposited TMSi2 (TM = Mo, Ta, Nb) films. The coatings were analyzed in terms of chemical composition, phase constitution, and mechanical properties (i.e. H and KIC) using diverse high-resolution characterization techniques. Moreover, the oxidation kinetics were systematically studied for all three systems at different temperature regimes up to 1500 °C. These analyses were supported by a detailed structural and morphological characterization of oxide scales formed.
HM 87
A new class of ultra-high temperature oxidation resistant coating materials: Si alloyed transition metal diborides
Glechner T.1, Hahn R.1, Bahr A.1, Wojcik T.1, Weiss M.2, Ramm J.3, Hunold O.3, Polcik P.4, Riedl H.1
1TU Wien, CDL-SEC, Austria
2TU Wien, Austria
3Oerlikon Surface Solutions AG, Liechtenstein
4Plansee Composite Materials GmbH, Germany
Surface protection of highly stressed components used in aviation or energy production is of great interest, especially to extend the operation ranges in oxidative high-temperature environments. Here, transition metal ceramics are a suitable class to resist such conditions. Combining a high temperature stable ceramic, such as TM-diborides, with the excellent oxide former Si was proven to result in coatings with outstanding oxidation resistance, tested up to 1500 °C. Various TM-Si-B2±z (TM=Ti, Cr, Hf, Ta, W) films were sputter deposited and subsequently oxidized in a DTA/TG setup to study the oxidation kinetics. Above certain Si contents Ti-Si-B2±z, Cr-Si-B2±z, and Hf-Si-B2±z exhibit strongly retarded oxidation kinetics with kp being below 10-11 kg2m-4s-1 at 1100 °C. Long term oxidation tests at 1200 °C (up to 60 h in ambient air on hard substrates) confirmed the protective ability of such coatings, with Hf0.20Si0.23B0.57 exhibiting an oxide scale thickness of only 1.5 µm after 60 h. Along with a broad set of high-resolution characterization techniques the study introduces this new class of coatings for oxidation protection at ultra-high temperatures.
HM 88
On the surpassing fracture toughness of TiB2±z thin films
Fuger C.1, Anna H.1, Rainer H.1, Tomasz W.1, Oliver H.2, Peter P.3, Helmut R.1
1TU Wien, CDL-SEC, Austria
2Oerlikon Surface Solutions AG, Liechtenstein
3Plansee Composite Materials GmbH, Germany
Their unique material characteristics make transition metal diboride-based thin films to perfect candidates for replacing state of the art protective and functional coatings. Well-known for their superior hardness, various TMB2 exhibit enhanced resistance against fracture exceeding KIC values of well-established nitride-based coating materials (e.g. TiN or Ti1-xAlxN). Here, we focus on magnetron sputtered non-stoichiometric TiB2±z exhibiting outstanding mechanical properties. Beside super hardness of 45.90 ± 1.20 GPa and Young’s modulus of 524.27 ± 14.10 GPa the coatings exhibit a fracture toughness of KIC = 4.79 ± 0.57 MPa√m. Detailed TEM and TEM-EELS investigations elucidate, that the distinct excess of boron predominates the constitution of the precipitating tissue phases around the columnar growth morphology. Due to covalently bonded boron-boron bonds the cohesive grain boundary strength is enhanced, impeding severe intercolumnar crack growth. The study highlights the great potential of TiB2±z for new applications in the field of high-performance components (e.g. as erosion resistant coating material) and reveal the importance of grain boundary strength for fracture tough thin films.
HM 89
Kinetics and thermodynamics study of Ti(C,N,O) coating by moderate temperature chemical vapor deposition (MT-CVD)
Zhu J.1, Zhang L.1, Yin L.2
1State Key Laboratory of Powder Metallurgy, Central South University, China
2Ganzhou Achteck Tool Technology Co., Ltd., China
In α-Al2O3-based CVD coating, TiCN and Ti(C,N,O)-based layers play an important role in the cutting performance and crystal growth of α-Al2O3 . As part of our work on high-performance α-Al2O3-based CVD coating, Ti(C,N,O) coatings from the TiCl4-CH3CN-H2-N2-CO system with varied CO addition were prepared by MT-CVD in Bernex BPXpro 530L CVD reactor. Growth rate of Ti(C,N,O) coating as a function of CO fraction in the feed gas was established. The experimental results show that CO reacts with TiCl4 under H2 atmosphere, which leads to the formation of TiC0.5O0.5. Thermodynamic calculation reveals that CO contributes to the HCN concentration increase in the gaseous phases during the CVD process. Grain refinement, growth rate increase and (111) preferred orientation of Ti(C,N,O) coating can be achieved by increasing CO fraction in the feed gas. Microstructure and growth dynamics regulation of Ti(C,N,O) are thought to be related to the co-deposition of TiC0.5O0.5 and the fraction of HCN in the gaseous phases, which will be discussed in detail. The thermodynamically predicted composition is in agreement with the experimental results.
HM 90
Investigation of the Origin of Stress Relaxation in Chemical Vapor Deposited TiCN
Konstantiniuk F.1, Tkadletz M.2, Waldl H.1, Krobath M.3, Ecker W.3, Czettl C.4, Schalk N.1
1Christian Doppler Laboratory for Advanced Coated Cutting Tools at the Department of Materials Science, Montanuniversität Leoben, Austria
2Department of Materials Science, Leoben, Austria
3Materials Center Leoben Forschung GmbH, Austria
4CERATIZIT Austria GmbH, Austria
Chemical vapor deposited TiCN is typically applied as a base layer below α-Al2O3 and represents one of today’s most used hard coating systems for cemented carbide cutting tools. It has been observed that the tensile residual stress in TiCN single layers, deposited at ~800 °C, is higher than in TiCN base layers below α-Al2O3, where the α-Al2O3 is grown at ~1000 °C. Thus, the aim of this work is to explore possible mechanisms responsible for this stress relaxation in TiCN and the effects on their mechanical properties, applying a combination of characterization methods. Complementary finite element simulations showed that creep in the Co binder of the substrate seems to only have a minor influence on the stress relaxation. Atom probe tomography was applied to confirm Co-diffusion from the substrate into TiCN, indicated by scanning electron microscopy. Nanoindentation experiments revealed that this Co-diffusion leads to a decrease of the hardness and Young’s modulus of TiCN. Finally, micro-cantilever bending experiments provided insights into the effect of this Co-diffusion on the fracture stress and fracture toughness of TiCN.
HM 91
Effects of coating-substrate interface roughness and thickness on damage accumulation in a hard-coated WC-Co hardmetal under cyclic shear-compression loading at 700°C
Maier K.1, Klünsner T.1, Walch L.1, Krobath M.1, Ecker W.1, Pichler P.1, Marsoner S.1, Czettl C.2
1Materials Center Leoben Forschung GmbH, Austria
2CERATIZIT Austria GmbH, Austria
Aim of the current work was to determine the influence of coating-substrate interface roughness and coating thickness on formation and growth of pores and cavities in a WC-Co hardmetal substrate below an Al2O3/TiCN coating. The specimens were subjected to cyclic high-temperature shear-compression loading. To this end, a novel ball-in-cone test method applied cyclic indentation in a servo-hydraulic testing machine in vacuum at 700 °C. The investigated substrate-coating composite was a WC-12 wt.% Co hardmetal with an average WC grain size of 2.0 µm covered with an Al2O3/TiCN hard coating layer by chemical vapor deposition. Nucleation and accumulation of defects in the nm- and µm-size regime was studied for the substrate by means of scanning electron microscopy in cross sections prepared by focused ion beam milling. The local loading situation in the contact area between hard-coated sample and spherical indenter was examined via finite element-based analysis. Effects of the degrees of roughness of the coating-substrate interface and the coating surface and also of the coating thickness on damage accumulation in the substrate will be discussed.
HM 92
Arc-PVD-Coatings with a thickness up to 25 µm for challenging machining applications
Frank H.1, Schulte A.1, Knipping T.2
1GFE - society of production engineering Schmalkalden, Germany
2MAS GmbH, Germany
PVD coatings are used during machining for wear protection of cutting tools. Thicker coatings leads to a better protection of the substrate against machining conditions, e.g. at higher temperatures, and a higher tool life. This means that thick layers can be used primarily for machining applications in steels and cast irons and for difficult-to-machine materials. Thick coatings are mainly produced by CVD processes. Usual PVD coatings reach thicknesses of approx. 5µm. At higher thicknesses, internal stresses and the reduced adhesive strength limit their use.
As part of different research projects, a technology was developed to deposit thick PVD coatings. By combining Arc-PVD with an additional sputtering process, the deposition characteristics were modified in a hybrid combination. These allows deposition of coating thicknesses of up to 25µm with a high reliably. Analyses have shown that these coatings have properties that are comparable to normal “thin” PVD coatings. Another important factor is the excellent wear behaviour of the thick coatings. The surfaces of the coatings can be modified by suitable post-treatment procedures to use in additional applications.
HM 93
Surface texturing and edge treatment of hardmetal tools by means of femtosecond pulsed laser
Sánchez-Moreno J.M.1, Castaño-Carmona E.1, Pan-Cabo A.1, Lozada-Cabezas L.1, Alkorta-Barragan J.1, Soria-Biurrun T.2
2Universidad de Navarra, Spain
Surface texturing of hardmetal components is being investigated as a way of improving subsequent coating adhesion or the lubrication of tribological contacts. A femtosecond pulsed laser has been used to modify the surface and the cutting edge of standard WC-Co cutting inserts. Conditions for generating laser induced periodic surface structures (LIPSS) have been analyzed (i.e. fluence, spot size, frequency, overlapping, etc.) in order to control the wave shape and orientation of the final texture. Industrial scale-up of laser surface texturing processes typically requires increasing the laser fluence in order to obtain the desired throughtput times. Much higher accumulated fluence is needed for edge micromachining operations (i.e. chamfering). The potential damage associated to both types of processes (i.e. LIPSS generation and edge micro chamfering) has been analyzed by means of the micro-slot drilling technique using a focused ion beam equipment (resolution: 5 squared microns). Validation of these measurements has been carried out by using the sin2psi technique.
HM 94
Microstructure and properties of PVD synthesized super-hard Ti-B-N coatings
Janknecht R.1, Hahn R.1, Kirnbauer A.1, Polcik P.2, Mayrhofer P.H.1
1TU Wien, Austria
2Plansee Composite Materials GmbH, Germany
Ternary transition-metal boron nitride Ti-B-N has emerged as an outstanding material system in the field of protective coatings due to its high hardness and temperature stability. In particular, its large number of equilibrium and metastable phases offers numerous possible compositions for investigating and understanding structural effects and their influence on mechanical properties.
With primary interest in chemical compositions close to the TiN-TiB line in the corresponding equilateral concentration triangle, Ti-B-N coatings were prepared using a Ti-TiN-TiB2 target containing 10 at.% B.
Focusing on the investigation of single-phase structured super-hard (H≥40 GPa) Ti-B-N coatings, the influence of various deposition conditions on the structure and mechanical  properties during non-reactive DC magnetron sputtering - compared to nanocrystalline Ti-B-N - comprises this study. The results show - consistent with previous ab initio calculations - that up to 10 at.% B can be incorporated into the face-centered  cubic (fcc) TiN lattice.
HM 95
Structure and properties of CVD layers deposited using the precursors AlCl3-NH3-CO2-H2 and different dopants
Höhn M.1, Gardecka A.2, Bäcke O.3, Halvarsson M.3
1Fraunhofer Institute IKTS, Germany
2Walter AG, Germany
3Chalmers tekniska högskola, Sweden
CVD-aluminium containing layers are one of the most important components in modern coating systems for cutting tools. In this work a precursor system containing AlCl3-NH3-CO2-H2 and dopants (e.g. TiCl4, SiCl4, ZrCl4) is used to deposit layers in a LPCVD process at substrate temperatures between 850°C and 1000°C. The coatings were characterized with respect to phase composition, crystal structure, hardness and wear behaviour. In dependence of substrate temperature and precursor ratio layers with nanocrystalline structure or layers with high textured crystals were obtained. Phase composition and structure were examined using TEM and EDX-analysis. The nanocrystalline coating consists of h-AlN with crystal sizes between 5 and 50 nm containing amorphous parts and an oxygen content of up to 25 at.%. The strongly textured coating shows strong columnar grains of h-AlN with an oxygen doping up to 15 at.%. With a hardness of up to 28 GPa the layers show a surprising high hardness level. The highly textured h-AlN coatings show good results in the turning of 56NiCrMoV7.
HM 96
Surface-reactions of iron-binder cemented carbides during CVD coating
Traxler M.1, Köpf A.1, Weissenbacher R.1, Lunzer M.1
1boehlerit GmbH & Co KG, Austria
Since health and environment legislation becomes more and more strict, the use of Cobalt as binder metal for cemented carbides is no longer a dogmatic fact. An increasing number of experiments and application tests show that iron is the prime replacement material as binder metal. Anyway, there are still some major questions concerning the use of iron especially in the context of machining tools. One of these is the behaviour of ironbound cemented carbides during high temperature CVD coating processes. This presentation will show some results of coating experiments with special regard to the possible occurrence of a carbon misbalance in the surface zone and/or the coating material. The eventual formation of carbon pores in the surface region of the cemented carbide together with the change of pure TiN coatings into TiCN are discussed. Furthermore, the influence of the addition of various mixed carbides to the substrate in different concentrations will be shown.
HM 97
High-resolution investigation of the microstructure and its correlation to the micro-mechanical properties of CVD thin hard coating, Ti(C,N) and Zr(C,N) case
El Azhari I.1, García J.2, Pauly C.1, Barrirero J.1, Valle N.3, von Fieandt L.2, Engstler M.1, Soldera F.1, Llanes L.4, Mücklich F.1
1Saarland University, Germany
2AB Sandvik Coromant R&D, Sweden
3Luxembourg Institute of Science of Technology, Luxembourg
4CIEFMA - Department of Materials Science and Engineering, EEBE - Polytechnic University of Catalonia (UPC), Spain
Ti(C,N) is one of the most used thin coating in metal cutting industry. Recently, through a multi-scale testing and characterization campaign, industrial cutting tools coated with Ti(C,N) is contrasted to Zr(C,N) in order to reveal the microstructural features that influence their behavior in industrial milling applications. It was found that the synergy of the following effects is responsible for the different response to comb crack wear: The more compatible coefficient of thermal expansion of Zr(C,N) with the substrate, better cohesive strength at the grain boundaries and plastic deformation. These factors assigned to the Zr(C,N) better structural integrity and fracture toughness during intermittent cutting. In the present work we shed the light on unexplored other characteristics related to the grain boundaries complexion and crystal shapes of these transition metal carbonitride. State of the art characterization techniques were used such as atom probe tomography (APT), high-resolution secondary ion mass spectrometry imaging (nano-SIMS) and 3D electron backscatter diffraction (EBSD). Strategies to tailor the microstructure of these compounds to enhance the ductility and maintain the strength are suggested.
17:00 - 20:00
Poster Session Hard Materials - Microstructure
Location: Poster Hall I
Show all Abstracts
HM 115
CFD-DEM simulation of melt pool formation and evolution in powder bed fusion process
Aminnia N.1, Estupinan Donoso A.1, Peters B.1
1Université de Luxembourg, Luxembourg
Computational models can be used to optimize metal additive manufacturing parts, and can also play a role in the evaluation of component quality. Among the most important components of such models will be the detailed simulation of flow and heat transfer in and around the melt pool that is formed when the powder bed is melted.  
In the present work, A Powder Bed Fusion process is studied numerically by using a coupled Computational Fluid Dynamics (CFD) model and eXtended Discrete Element Method (XDEM) model to predict the physical behavior of discrete particles and the melt pool. In XDEM, a randomly packed powder bed of spherical particles is generated and heat and momentum exchange of each particle with other particles and the melt pool are calculated. The CFD model will predict the effects of laser-melt and powder-melt interactions on the melt pool dynamics. Using the developed numerical framework, it will be possible to determine how powder size distribution, the velocity of a laser beam, and the power, among other factors, will affect the characteristics of melt pool.
HM 116
Influence of carbon content on the binder microstructure in WC-Co-Ru cemented carbides
Olovsjö S.1, Qvick J.1
1Seco Tools, Sweden
The influence of the carbon content on the binder microstructure of WC-Co-Ru cemented carbide was investigated. Different C/W ratios were considered to investigate the influence of the carbon content on binder microstructure, the compositions were varied from 3 phase W- rich to 3 phase C– rich. The experiments were based on the hypothesis that the amount of tungsten dissolved in the binder phase will affect the transformation temperature and thereby the amount of hcp phase in the binder phase. The influence of the cooling rate from the liquid phase sintering temperature was also considered and investigated. Coercivity and magnetic saturation were measured and reported. The microstructure properties were investigated with scanning electron microscopy - electron backscattering diffraction (EBSD). The result shows that an increased amount of tungsten dissolved in the binder promotes the hcp phase formation while an increased amount of C favours the fcc phase in the binder.
HM 117
Effect of WC grain size distribution on cemented carbide structure and performance
Ivarsson F.1, Lilja M.2, Borgh I.2
1KTH, Royal institute of technology, Sweden
2Sandvik Mining and Construction Tools AB, Sweden
Cemented carbides are a composite material used in applications such as cutting tools and rock drilling inserts, produced through liquid-phase sintering. Traditionally, the material consists of WC grains embedded in a Co-rich binder phase. The size and distribution of the WC grains will affect the structure and the mechanical properties of the material. Thus, in this work modelling alloys with different WC grain size distributions have been produced, with the aim to answer whether it is possible to change the material properties by changing the WC grain size distribution. The effect of powder process parameters on microstructure evolution and mechanical properties has been investigated and compared to reference grades. Different characterization techniques, e.g. scanning electron microscopy, and mechanical testing were employed to study the model alloys and the results will be discussed.
HM 118
Oxidation mechanism of TiSiN and TiAlSiN coatings investigated by in-situ X-ray diffraction
Moritz Y.1, Saringer C.1, Tkadletz M.2, Stark A.3, Schell N.3, Czettl C.4, Pohler M.4, Schalk N.1
1Christian Doppler Laboratory for Advanced Coated Cutting Tools at the Department of Materials Science, Montanuniversität Leoben, Austria
2Department of Materials Science, Montanuniversität Leoben, Austria
3Institute of Materials Physics, Helmholtz-Zentrum Hereon, Germany
4CERATIZIT Austria GmbH, Austria
TiSiN and TiAlSiN hard coatings are known to exhibit a high oxidation resistance, owing to their nanocomposite structure consisting of Ti(Al)N nanocrystals embedded in an amorphous SiNx tissue phase. In this work, the oxidation mechanism of a powdered TiSiN and two powdered TiAlSiN coatings with low Al contents was investigated by in-situ X-ray diffraction (XRD) complemented by differential scanning calorimetry. Rietveld refinement of the obtained XRD data allowed to monitor the evolution of the phase composition during the oxidation process in the range of 100 to 1200 °C. Additionally, the microstructure of solid oxidized TiSiN and TiAlSiN coatings was investigated, revealing a high oxidation stability for both TiSiN and TiAlSiN coatings, whereby an increasing Al content was found to further delay the oxidation onset. The formation of the metastable anatase TiO2 phase was observed for all coatings, which transformed into the stable rutile TiO2 modification at higher temperatures. The present findings provide a comprehensive overview of the oxidation behaviour of TiSiN and TiAlSiN coatings, highlighting their excellent suitability for the cutting industry.
HM 119
Oxidation resistance of cathodic arc evaporated Cr0.74Ta0.26N coatings
Kainz C.1, Saringer C.1, Burtscher M.2, Tkadletz M.2, Stark A.3, Schell N.3, Pohler M.4, Czettl C.4, Kiener D.2, Schalk N.1
1Christian Doppler Laboratory for Advanced Coated Cutting Tools at the Department of Materials Science, Montanuniversität Leoben, Austria
2Department of Materials Science, Montanuniversität Leoben, Austria
3Institute of Materials Physics, Helmholtz-Zentrum Hereon, Germany
4Ceratizit Austria GmbH, Austria
The microstructure, mechanical and tribological properties of CrTaN coatings grown by physical vapor deposition have been recently investigated in detail. However, the oxidation mechanism of CrTaN is not well understood up to now. Thus within this work, the oxidation sequence of a Cr0.74Ta0.26N coating grown by cathodic arc evaporation was studied in a combinatorial approach applying high energy X-ray diffraction and transmission electron microscopy (TEM). The as-deposited Cr0.74Ta0.26N coating crystallizes in the face-centered cubic (fcc) structure and withstands temperatures as high as 1050 °C without evidence of oxidation. Upon further increasing the temperature, tetragonal (t) CrTaO4 and rhombohedral (r) Cr2O3 form at the expense of fcc-CrTaN, which is entirely consumed at ~1270 °C. TEM investigations on a solid CrTaN coating oxidized at 1225 °C revealed intact fcc-Cr0.76Ta0.24N close to the substrate, an intermediate porous layer consisting of t-CrTaO4 as well as r-Cr2O3 and a protective r-Cr2O3 oxide scale at the surface. The present work demonstrates the exceptional oxidation resistance of CrTaN coatings and thus demonstrates their high potential for use in severe cutting applications.
HM 120
Inverse Pole Figure of CVD a-Al2O3 Using XRD Bragg Brentano Geometry
Shibata T.1
1Kennametal, USA
CVD coated cemented carbides are widely used for various metal cutting applications and it is now established that the textures of the coating materials especially α-Al2O3 greatly affect the cut performance, and characterization of texture is thus very important. In this paper inverse pole figures (IPF) of α-Al2O3 are calculated based on XRD with standard Bragg Brentano geometry for several commercially available metal cutting inserts. This method is simple, less time consuming than from the analysis of the pole figure from XRD or EBSD in SEM, and can be applied to available standard XRD data. The obtained IPF is consistent with the EBSD method with some differences and limitations, but qualitative description is mostly sufficient. Comparison with EBSD based IPF methods, and IPF of representative historical products will also be presented.
HM 121
Evolution of the fracture behavior of arc evaporated Ti1-xAlxN coatings with increasing Al content
Waldl H.1, Tkadletz M.2, Lechner A.2, Czettl C.3, Pohler M.3, Schalk N.1
1Christian Doppler Laboratory of Advanced Coated Cutting Tools, Montanuniversität Leoben, Austria
2Department of Materials Science, Montanuniversität Leoben, Austria
3CERATIZIT Austria GmbH, Austria
While the effect of an increasing Al content on the hardness of Ti1-xAlxN hard coatings is comprehensively investigated, no systematic studies on the fracture properties are available. Thus within the present work, a series of Ti1-xAlxN coatings (TiN, Ti80Al20N, Ti60Al40N, Ti50Al50N, Ti40Al60N, Ti33Al67N, Ti20Al80N) was synthesized by cathodic arc evaporation and the fracture stress and toughness were determined by micromechanical bending tests on free-standing coating cantilevers. Subsequently, the obtained fracture properties were correlated with the microstructures and phase compositions, determined by scanning electron microscopy and X-ray diffraction. These experiments revealed a slight increase of fracture stress and toughness with increasing Al content, as long as the face-centered cubic structure dominates, while for coatings with higher Al contents, exhibiting a dominating wurtzitic structure, the fracture properties deteriorate. Illuminating the fracture properties of Ti1-xAlxN coatings over a wide compositional range, the present work fills an existing gap in the otherwise comprehensive literature on this coating system.
HM 122
Improved adhesion of cathodic arc PVD AlCrSiN coating with ion implanted WC-Co substrate
Ortiz Membrado L.1, García González S.1, Liang J.1, Orrit Prat J.2, Bonet R.2, Caro J.2, Fernández de Ara J.3, Almandoz E.4, Llanes L.5, Jiménez-Piqué E.5
2Eurecat, Spain
3AIN, Spain
5CIEFMA-UPC and Barcelona Research Center in Multiscale Science and Engineering, Spain
Adhesion strength is an important property required for coated cutting tools to work efficiently. Ion implantation pre-treatment of the substrate has been reported to improve adhesion strength of the coating due to a synergic improvement on fracture toughness and compressive residual stress generation. In this work, AlCrSiN coatings deposited by PVD on WC-Co substrates implanted with Ti, Cr and N have been mechanically tested and microstructurally characterized. Residual stress of the coatings was evaluated using FIB-DIC technique and adhesion strength has been compared by means of scratch and Mercedes test. An improvement of adhesion strength was obtained for implanted samples, and especially the titanium and chromium implanted samples show the best resistance, for which a higher value of fracture toughness of the substrate was calculated.
HM 123
Effect of annealing on the microstructure and mechanical properties of Ti0.17Al0.83N coating prepared by low pressure chemical vapor deposition
Zeng F.1, Qiu L.2, Du Y.1
1Central South University, China
2Ganzhou Achteck Tool Technology Co. Ltd., China
The fcc Ti0.17Al0.83N coating was deposited on cemented carbide insert by LPCVD method. The effects of annealing temperature and atmosphere on the surface and fracture morphology, phase structure, residual stress, and hardness of the Ti0.17Al0.83N coating were studied. TEM analysis indicated that the as-deposited Ti0.17Al0.83N coating was self-organized with a periodically alternating Al-rich (9 nm) and Ti-rich (2 nm) nanolamellae. With the rise of vacuum annealing temperature from 700 to 1200◦C, the coating hardness was increased and then decreased while the compressive residual stress was increasing continuously. Maximum hardness of 46.5 GPa was obtained after annealing in vacuum at 900 ◦C for 1 h. The coating grains cracked with the compressive residual stress of − 1.55 GPa after annealing in vacuum at 1100 ◦C for 1 h. The surface morphology of the coating was basically unchanged after annealing in air at 900 ◦C for 1 h, while it was completely oxidized with the formation of Al2O3 on the surface
after annealing at 1000 ◦C.
HM 124
Correlation between mechanical integrity at the superficial length scale vs. superficial roughness in WC-Co cemented carbides
Riu Perdrix G.1, Sarsanedas M.2, Weil D.3, LLanes Pitarch L.M.4, Johanns K.E.5, Oliver W.C.5, Roa Rovira J.J.1
2Steros Drylyte S.L., Spain
3KLA-Tencor GmbH, Germany
4Universitat Politècnica de Catalunya, Spain
5KLA Corporation, USA
The unique combination of hardness, wear resistance and toughness exhibited by hardmaterials have made them preeminent material choices for extremely demanding applications. This presentation is focused in particular on WC-Co. A large number of studies have been reported, mainly focused on the corrosion behaviour of the metallic binder in contact with acid or even neutral media. Within this context, a new dry-electropolishing electrolyte has been developed to be employed in the DryLyte® technology that allows to obtain corrosion-free surfaces with a roughness below 9 nm. The main goal behind this research is to investigate the compressive residual stress as well as the hardness evolution as a function of the dry-electropolishing time. A statistical methodology has been implemented and the quality of the surface have been evaluated by using advanced characterization techniques. To sum up, a close correlation is observed between the compressive residual stress state and the mechanical integrity in terms of hardness as a function of the polishing time. On the other hand, the elastic modulus remains unchangeable for the different investigated steps.
HM 125
Physical, Microstructure, and Mechanical Property Effects of Molybdenum Addition to NbC-TiC-Ni and WC-TiC-Co Cemented Carbide Binders
Rabothata M.1, Mphasha N.2, Genga R.1, Huang S.3, Vleugels J.3, Nelwalani N.4, Janse van Vuuren A.5, Polese C.6
1Academic Development Unit, University of the Witwatersrand, South Africa
2School of Chemical and Metallurgical Engineering, University of Witwatersrand, South Africa
3Department of Materials Engineering (MTM), KU Leuven, Belgium
4School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, South Africa
5CHRTEM, Nelson Mandela University, South Africa
6School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand, South Africa
The effects of liquid phase sintering (LPS) and pulsed electric current sintering (PECS), the addition of TiC as a secondary hardening phase, and 30 wt% of binder phase substitution by Mo were investigated to improve the physical, microstructure, and mechanical properties of NbC-Ni and WC-Co based cermets. Grain size refinement was achieved through additions of TiC and Mo as well as PECS, with reductions from ~5 µm to <1 µm in NbC cermets, giving an HV30 hardness >14 GPa and fracture toughness (KIC) > 7MPa.m1/2. Molybdenum addition inhibited densification in all NbC compositions irrespective of the sintering technique. The Ni/Mo (70/30) binder phase however improved the KIC in all NbC cermets. Microstructure analyses were conducted by high-resolution scanning electron microscopy (SEM), Annular darkfield (ADF) scanning transmission electron microscopy (STEM), and Transmission electron microscopy (TEM) to better understand the role and the location of Mo in the binder phase. The NbC cermets had lower elastic and shear moduli than the WC-based materials, irrespective of the sintering technique.
17:00 - 20:00
Poster Session Refractory Metals - HIP, HP and SPS
Location: Poster Hall I
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RM 79
Self-diffusion and oxygen diffusion in refractory alloys
Wilde G.1, Divinski S.1, Seiß M.2
1University of Münster, Germany
2Plansee SE, Austria
Kinetic data of solids, as given by the results of diffusion measurements, are of high importance for a broad range of issues from synthesis and processing to mechanical performance, microstructure stability or corrosion resistance. In this respect, tracer diffusion is one of most reliable and important methods, since it allows for measuring self-diffusion coefficients. Secondary-Ion-Mass-Spectroscopy (SIMS) profiling, on the other hand, allow accessing diffusivities of elements where no suitable radio-tracer exists.
The present contribution focuses on diffusion measurements in refractory alloys. Specific examples are highlighting new conceptual developments based on combined tracer/inter-diffusion measurements. It is shown that this approach offers possibilities to provide concentration-dependent tracer diffusion coefficients of the constituting elements in multi-component alloys in high-throughput experiments. One example is given by Oxygen diffusion in Ta-rich alloys, relating to the stability in service. Another example refers to refractory high entropy alloys, where the understanding their diffusion properties is of vital importance to assess the environmental resistance and deformation characteristics, with specific attention to the ductile-brittle transition and possible “sluggish-diffusion” effects in this class of alloys.
RM 80
SPS Special Effect and Application in Advanced Powder Metallurgy Materials
Jiuxing Z.1, Yafei P.1, Cuiliu H.1, Xinyu Y.1, Binrong N.1, Zhengwan W.1, Dapeng S.1, Junkang Z.1
1hefei university of technology, China
Spark Plasma Sintering (SPS) is a new and highly efficient sintering/joining technique for advanced powder metallurgy materials. In this paper, we firstly take introduction to SPS special effects including nanocrystalline dense bulk, SPS chemistry, nano-micro grains controlling, amorphous bulk densification, FGM sintering. It is showed that the SPS has special and different mechanisms from the HP and HIP, and can be used in research and development of advanced powder metallurgy materials. Then, we show the results and discussion of rare earth hexaborids (REB6) single materials, CT target, WC materials, copper-diamond composite materials, as well as the joining of tungsten and molybdenum alloy, which demonstrate the SPS promising application in industry.
17:00 - 20:00
Poster Session Hard Materials - Hardmetals and properties
Location: Poster Hall I
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HM 107
Mechanical properties of WC carburized at elevated temperatures, under nitrogen
Jewett T.1, Hippe F.2, Payne B.3
1Global Tungsten &amp; Powders Corp., USA
2Ceratizit, Luxembourg
3Global Tungsten & Powders, USA
Carburizing tungsten metal powder at temperatures above standard, based on production norms, increases the average tungsten carbide, WC, grain size.  That increase in grain size will, in turn, affect the sintered properties of WC-Co cemented carbides, of which the mechanical properties are of considerable interest.  The present investigation evaluates the change in all sintered properties of cemented carbides produced from a range of WC particle sizes, 2.0 – 13.5 microns by FSSS.  The WC materials were carburized from over a range of elevated temperatures in nitrogen.  The changes in the WC grain size and morphology are correlated to the change in mechanical behavior, such as hardness, TRS, fracture toughness and wear response.  As a point of comparison, the current samples were compared to standard production WC, produced under hydrogen.
HM 108
On the prediction of hardmetals corrosion based on their binder response
Ferro Rocha A.1, Pereira P.2, Santos A.1, Oliveira M.1, Sacramento J.3, Senos A.M.1, Bastos A.1
1University of Aveiro, Portugal
2University of Porto, Portugal
3DURIT - Metalurgia Portuguesa do Tungsténio, Lda., Portugal
This communication presents a systematic comparison of the corrosion resistance of a series of WC hardmetal composites with the corrosion behaviour of the respective binders. Pure metals and alloys of Co, Ni and Cr were produced by pulverometallurgy. Hardmetal composites were produced with the same metals and alloys as binders. The corrosion of the hardmetals and binders was characterised by electrochemical techniques such as open circuit potential monitoring (OCP), potentiodynamic polarisation (PC) and electrochemical impedance spectroscopy (EIS), complemented by optical and electron microscopies. The objective was to verify to which extent it is possible to predict the corrosion behaviour of hardmetals based solely on the response of the binder.
HM 109
Solubility of V and Cr in Fe-Co-Ni binders and properties of corresponding hardmetals
Wagner S.1, Buchegger C.2, Bohn M.3, Lengauer W.4
1Hartmetall Estech AG, Switzerland
2W&H Dentaltechnik, Austria
3Université de Bretagne Occidentale, France
4Vienna University of Technology, Austria
The Fe-Co-Ni binder system of hardmetals was investigated for the solubility of grain-growth inhibitors V and Cr. This was performed by preparation of 24 model alloys with high binder-phase content facilitating the composition measurement. Free VC and Cr3C2 (or M7C3) were present for fixing the V and Cr concentrations at the maximum. Carbon concentration for each sample was adjusted to precipitate η-phase or free carbon, respectively, for a fixed carbon activity at low (η-phase) and high (free C) level. This defines the maximum or minimum solubility of various elements in the binder phase, too. The model alloys were checked by XRD and metallography for presence of the various phases and then subjected to WDS-EPMA (wavelength-dispersive electron probe microanalysis). To explore the possible application areas of each binder alloy the solubility data served as a basis for subsequently optimising properties of Fe-Co-Ni binder hardmetals of which hardness, fracture toughness, coercivity, magnetic saturation as well as density and porosity were measured. Furthermore, properties of hardmetal with four different binder alloys were analysed throughout the carbon window.
HM 111
Measurement of microscopic residual stresses in binder phase of WC-Co hard metals
Rudenskiy D.1, Bezold A.1, Christoph B.1
1RWTH Aachen University, Germany
It is well known that WC-Co hard metals exhibit a pronounced residual stress state at room temperature. Obtaining the exact stress distribution experimentally is still a challenging task. The averaged values of these as type 2 or microscopic classified residual stresses are considered to be tensile in the cobalt binder and compressive in the WC phase. However, only the stresses in the WC phase are accessible by diffractometry as Co lattice parameter varies due to solid solution of W and C atoms. In this study digital image correlation (DIC) is used in combination with focused ion beam (FIB) for estimation of binder stresses. This method referred as micro-ring-core drilling implies measurements of displacement fields based on SEM images coupled with finite element simulation. Measurements were performed on WC6wt.%Co and WC20wt.%Co samples, adopting the methodology to hard metal specific microstructure. In earlier studies based on analytical models, significant residual stresses in the binder phase were expected. However, our measurements show rather moderate residual stresses, comparable in magnitude to those of the WC phase.
HM 112
Features of high temperature deformation of pure tungsten carbide ceramics with different grain sizes
Lantsev E.1, Nokhrin A.1, Chuvil`deev V.1, Boldin M.1, Blagoveshchensky Y.2, Murashov A.1, Smetanina K.1, Isaeva N.2
1Lobachevsky State University of Nizhny Novgorod, Russia
2Baikov Institute of Metallurgy and Materials Science, Russia
The mechanism of high-temperature deformation in the creep mode during compression tests of tungsten carbide samples with different grain sizes has been studied. Samples with a high relative density (96.1-99.2%) were obtained by the method of high-speed spark plasma sintering (SPS) from nano-, submicron, and micron α-WC powders. Creep tests were carried out in two modes: isothermal holding at different temperatures (1300-1375°C) at a given pressure to estimate the creep activation energy, and tests by the "stress surges" method at a temperature of 1325°C. It is shown that the creep activation energy of ultrafine-grained (UFG) tungsten carbide with a grain size of ~ 0.15 μm, sintered from plasma-chemical nanopowders, is ~31 kTm. This value is 1.5-2 times higher than the activation energy of creep of samples from submicron (~ 0.8 μm) and micron (~ 3 μm) industrial powders. It was found that the value of the coefficient n varies from 2.4 to 3.1, which corresponds to the case of motion of lattice dislocations in the field of uniformly spaced point obstacles.
HM 113
The problem of decarburization of nanocrystalline WC and methods of its solution
Batenkova A.1, Kurlov A.1
1Institute of Solid State Chemistry of the Ural Branch of the RAS, Russia
The large specific surface area of nanocrystalline WC powders determines their high chemical activity thus making them prone to impurities accumulation. Oxygen is the most harmful one, as it partially decarburizes WC during sintering producing CO and CO2 gases that cause pores formation.
Current work compares three methods of preventing the decarburization in nanocrystalline WC upon heating: adding extra carbon for a direct carbon loss compensation, adding metallic Al to bind impurity oxygen into Al2O3 and adding ZrC to compensate for the carbon loss and to bind impurity oxygen into ZrO2. High-energy ball milling was employed to produce nanocrystalline WC and abovementioned mixes. Characterization of the powders and sintered samples were carried out using XRD, BET, chemical analysis, SEM, pycnometry, the Vickers method. Simultaneous thermal analysis was used to study sintering processes.
Research has shown that all three methods allow preventing heavy decarburization of WC and preserving its single-phase structure during sintering. It has been found that even small additives noticeably change properties of the samples sintered from nanopowders.
HM 114
Correlative microscopy and machine learning – new tools for material characterization
Fitzek H.1, Schmidt R.1, Nachtnebel M.2, Rattenberger J.2, Zankel A.1, Hofer F.1, Schroettner H.1
1Graz University of Technology, Austria
2Graz Centre for Electron Microscopy (ZFE), Austria
The correlation of different microscopic techniques has seen increased interest in recent years due to the possibility of combining the strengths of multiple techniques. In addition to the practical challenges with regard to sample preparation, instruments design and the need for operators experienced in multiple techniques, unique data treatment challenges arise when combining data sets with different resolutions and contrast mechanism. Two key questions arise. First, how can images and mappings with vastly different pixel resolutions, data format and pre-treatment requirements be combined into a single dataset? Second, how can the resulting combined map that consists of techniques with different physical meaning and phase dependent significance be evaluated?
We want to address these questions on the example of Raman-SEM-EDS. Using specific examples we will not only talk about correlating and combining the data sets, but also point out the benefits of doing so and how to leverage machine learning for an optimal evaluation. Please note that the presented approaches generalizes to other combinations of microscopic techniques.
17:00 - 20:00
Poster Session Hard Materials - Powders and P/M processes
Location: Poster Hall I
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HM 99
Reactive sintering of 3D printed structures of cemented carbide
Stanciu V.I.1, Mégret A.1, Vitry V.1, Fabienne D.1
1University of Mons, Belgium
Cemented carbides are very interesting materials for tools and 3D printing of this materials is a technology that will allow making tools with complex geometry at affordable prices.
The refractory nature of tungsten carbide makes 3D printing of this product by usual metallic additive manufacturing methods very difficult, a reason to look for an alternative. The production of a tungsten-carbon-cobalt mixture (in which grain growth inhibitors could be added) followed by reactive sintering to consolidate and at the same time transform the tungsten-carbon mixture into carbide seems attractive because this mixture is much less difficult to mill/mix and can be used in a classic 3D printing method.
The preparation of the mixtures  was done by planetary ball milling during 10h with minimal wear using steel balls and jars instead of WC-Co ones. Tests have shown that the tungsten carburizing reaction takes place successfully during sintering at a temperature of 1450°C for 1h. Samples were shaped by extrusion using paraffin as lubricating agent.
HM 100
Spark plasma sintering of nanopowders based on tungsten carbide with different amount of adsorbed oxygen
Lantsev E.1, Nokhrin A.1, Chuvil`deev V.1, Blagoveshchensky Y.2, Murashov A.1, Smetanina K.1, Terentiev A.2, Isaeva N.2
1Lobachevsky State University of Nizhny Novgorod, Russia
2Baikov Institute of Metallurgy and Materials Science, Russia
The influence of adsorbed oxygen on the properties of samples and the kinetics of spark plasma sintering of pure tungsten carbide and hard alloy powders has been investigated. It is shown that oxygen leads to the formation of W2C and η - phases in pure tungsten carbide and in hard alloys, respectively. It was found that adsorbed oxygen does not significantly affect the shrinkage kinetics of powder compacts. The activation energy of the intensive second stage of sintering of pure tungsten carbide and hard alloy powders was 9 and 12 kTm, respectively. Samples of pure tungsten carbide were characterized by high values of hardness (near 25 GPa) and crack resistance (4.7 MPa*m1/2).
HM 101
Colloidal processing of tungsten and tungsten carbide powders in water media
Garcia-Ayala E.M.1, Eguiluz A.1, Ferrari B.1, Sanchez-Herencia A.J.1
1Institute for Ceramic and Glass ICV-CSIC, Spain
Advances in current and new technologies commonly require to expand the limits in use of materials, especially if those are very severe. In this sense the strategies to design and manufacture complex microstructures require of innovative processing approaches to ensure controlled dispersion of phases, not only with different compositions but sizes and shapes. Aqueous colloidal processing techniques are some the most versatile techniques to process complex structures with mixture of powders in a clean and zero-emissions environment. Controlling the conditions of the media the physic-chemical surface of the mixture of powders can be processes in slurries where the different compositions, sizes and shapes are milled to fabricate powders and feedstock that can easily transferable industrial productions. In this paper the use of colloidal techniques to disperse tungsten and tungsten carbide in water is presented as a way to prepare the powders for sintering as well as to mix with other metallic powders to achieve new microstructures after sintering.
HM 102
Extrusion of hardmetal pastes through twisted extrusion dies
Ayton H.C.1, Sutcliffe M.P.F.1, Müller P.2, Schaefer J.2, Wilson D.I.1
1University of Cambridge, United Kingdom
2Ceratizit Austria GmbH, Austria
Ram extrusion of hardmetal pastes through cylindrical dies with twisted internal fins imparts rotation to the extrudate which is desired for certain applications.  This paper presents a simplified model for the work required to extrude a paste through such a die based on the Benbow-Bridgwater approach to describe paste flow.
The model predictions are compared with experimental data obtained from extrusion testing of (i) a commercial hardmetal paste through precision-machined tungsten carbide dies, and (ii) a softer pharmaceutical paste through metal 3-D printed dies. The agreement between the model predictions for (i) was reasonably good, while the agreement in (ii) was poorer, owing principally to the rough die land surfaces generated by 3-D printing.
The model is compared with detailed FEM simulations of extrusion through twisted dies: some of the challenges in obtaining reliable results with such codes are discussed.
HM 103
Reducing cobalt capping on hard metals using CO sintering
Kumba Premkumar V.B.1
1Seco Tools AB, Sweden
Cemented carbide inserts are sometimes covered with a thin layer of cobalt binder on their surface. This phenomenon is called cobalt capping, which occurs due to the liquid phase migration of cobalt in the material during the cooling stage in the sintering processes. Although, there is no univocal explanation as to why cobalt migrates, it is prevalent that it does so to reduce the total interfacial energy of the system. Fine grained WC materials are especially prone to cobalt capping, probably due to their high interfacial energy in the system. This study focuses on eliminating cobalt capping by introducing carbon monoxide gas during sintering. CO gas carburizes the surfaces of the material, which liquifies the solid Co layer, when the temperature of the material is at the 3-phase region of the phase diagram. This creates an imbalance between the volume of liquid cobalt on the surface against the fractional solid and liquid cobalt in the bulk, causing liquid cobalt on the surface to migrate inwards homogenously, without resulting in a cobalt gradient.
HM 104
Influence of wettability of tungsten carbide powder by organic binder/additives on the quality of filaments for Material Extrusion (MEX)
Alves B.1, Gatões D.1, Fernandes C.2, Figueiredo D.2, Senos A.3, Vieira M.T.1
1University of Coimbra, Portugal
2Palbit, S. A., Portugal
3University of Aveiro, Portugal
Material extrusion (MEX) integrates the ongoing effort to improve Additive Manufacturing (AM) sustainability. Nowadays, MEX has been gaining increasing interest for manufacturing cutting tools. The inner and outer surface quality of this process overcomes some conventional fabrication impossibilities, as it allows the building of different and efficient cooling systems inside the tool. MEX is one of the indirect AM processes where the feedstock preparation assumes the main role to attain cutting tools with outstanding properties. The wettability of hardmetal (WC) by organic binder/additive systems was evaluated by the contact angle measurements at selected temperatures, depending on the polymers used in feedstock. The mixing with organic liquid during feedstock preparation can induce significant heterogeneities in particles powder distribution in the extruded filament. The migration of binder/additives from selected powder particles is presumably caused by the wettability difference. The decrease of wettability can also be affected by the addition of metal binder in hardmetal composition. Microtomography was the selected technique to highlight the different behaviour with respect to homogeneity of particle powder distribution in the filament after extrusion.

Funding: This research is sponsored by FEDER funds through COMPETE, Programa Operacional Factores de Competividade, 3DCompocer (POCI-01-0247-FEDER-047060), and by national funds provided by FCT, Fundação para a Ciência e Tecnologia, (project references UIDB/00285/2020) and Centro2020 through PAMI—ROTEIRO/0328/2013 (no. 022158).
HM 106
Spark plasma sintering of different composition WC-Co plasma-chemical nanopowders
Isaeva N.1, Blagoveshchenskiy Y.1, Terentev A.1, Lantsev E.2, Smetanina K.2, Nokhrin A.2
1IMET RAS, Russia
WC nanopowders with average size of 60 nm were produced by plasma-chemical method. WC-Co mixture with various Co (4, 6, 10 wt%) were fabricated. Two variations of additives (VC+TaC or Cr3C2+TaC) were used. The powders were certified by SEM and XRD.
The preparation of WC-Co hard alloys was carried out by SPS method in solid-phase and liquid-phase sintering modes with holding at 900°C for degassing.
The method of WC-Co mixture obtaining (high energy ball milling and chemical precipitation) was investigated. It is shown that chemical deposition provides more uniform distribution of Co. SPS provides density close to theoretical. The microstructure of the material after solid-phase sintering is ultrafine-grained. The alloys with Cr3C2+TaC ensures high values of hardness and fracture toughness (21.8 GPa and 11.7 MPa*m1/2 for WC-10% Co; 26.6 GPa and 9.7 MPa*m1/2 for WC-6% Co; 27.9 GPa and 8.9 MPa*m1/2 for WC-4% Co). The addition of VC provides finer-grained microstructure and higher Hv and K1C in both modes.
The sintering curves were analyzed using the Yang-Cutler model and the activation energies were determined.
17:00 - 20:00
Poster Session Hard Materials - Applications
Location: Poster Hall I
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HM 62
A comparative study on the cutting performance of newly developed NbC containing inserts and WC-Co inserts in high speed dry turning C45 steel
Peeters B.1, Bert L.1, Jef V.1, Shuigen H.1
1KU Leuven, Belgium
In this research, an investigation is performed to validate whether NbC containing cermets are viable replacements for WC-Co in high-speed dry turning of C45 steel. This study focuses on a comparative study of the cutting performance of 7 insert grades, including a NbC-Ni based cermet, two TiCN-NbC based cermets, developed at KU Leuven, and commercially available TiCN-based as well as WC-Co inserts with/without a coating. The cutting forces, surface temperature, and flank wear of the inserts were evaluated during turning at three different cutting speeds (250, 325, and 400 m/min) with a depth of cut of 1 mm. These data are used in combination with XRD, EDX, and microstructural analysis to analyze the cutting performance and the failure modes of the different types of inserts. The results indicated that the uncoated NbC-Ni based insert outperform the uncoated WC-Co insert and the TiCN-NbC based insert outperforms the coated WC-Co insert as well as comercial TiCN based insert when dry cutting of C45 steel.
HM 63
Dry Turning of AISI 1213 Structural Steel Using Uncoated TiC7N3 and WC Enhanced NbC-Based Inserts
Genga R.1, Zeman P.2, Brajer J.2, Malý J.2, Primus T.2, Pešice M.2, Huang S.3, Vleugels J.3, Janse Van Vuuren A.4
1Academic Development Unit (ADU), University of the Witwatersrand; School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand; DST-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, South Africa
2Department of Production Machines and Equipment (RCMT), Faculty of Mechanical Engineering, Czech Technical University in Prague, Czech Republic
3Department of Materials Engineering (MTM), KU Leuven, Belgium
4Centre for HRTEM, Nelson Mandela University, South Africa
Structural steels are used in several industrial applications ranging from construction to transport due to their good combination of tensile strength, durability, corrosion resistance and affordability. Here, NbC hardmetals with grain growth inhibitors (TiC and Mo2C) as well as TiC7N3 and WC secondary hardening phases were investigated as potential inserts for turning of AISI 1213 structural steel. The NbC inserts performances were compared to WC-Cr3C2-Mo2C-TiC-Co based inserts. Dry semi-finishing and finishing turning of AISI 1213 structural steel was conducted at cuttings speeds (vc) of 200–300 m/minute, depths of cut (ap) of 0.25–0.5 mm and feeds between 0.1-0.15 mm/rev. Insert wear was characterized by optical microscopy, 3D crater wear mapping, scanning electron microscopy (SEM) and annular dark field (ADF) scanning transmission electron microscopy (STEM). Additions of TiC7N3 and WC to NbC-Ni and PECS significantly improved the turning performance, resulting ~25% longer tool life than WC-Cr3C2-Mo2C-TiC-Co based inserts during semi-finishing (vc=200 m/min, ap=0.5 mm) giving a maximum flank wear (VBmax) of <500 µm after 20 minutes, and >50% longer life during finishing (vc=300 m/min, ap=0.25 mm).
HM 64
Influence of the cutting edge radius on tool wear during cryogenic machining with cemented carbide end mills
Gutzeit K.1, Müller D.1, Kirsch B.1, Aurich J.C.1
1Technische Universität Kaiserslautern, Germany
The titanium alloy Ti-6Al-4V is widely used in industrial applications, due to an excellent ratio of low density to high strength and a strong corrosion resistance. However, Ti-6Al-4V is a hard to machine material because of its low thermal conductivity and high chemical reactivity. These material properties lead to high demands on the tool. To enhance the cutting performance, cemented carbide tools with rounded cutting edges can be used, as the strength of the cutting edge is improved. However, higher cutting edge radii favor ploughing effects, increasing the thermal load and in turn the tool wear. By using a cryogenic cooling, the thermal load is reduced significantly, offering the potential to counteract the disadvantage of the cutting edge preparation.
In our investigations, Ti-6Al-4V is milled using cemented carbide end mills while the cutting edge preparation and the cryogenic cooling strategy are systematically varied. The aim is to extend tool life by a suitable combination of cryogenic cooling and cutting edge preparation. This is assessed by evaluating the resulting tool wear.
17:00 - 20:00
Poster Session Refractory Metals - Materials
Location: Poster Hall I
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RM 35
Influence of heat treatment conditions on magnetic, thermal and electrical properties of tungsten heavy alloys
Edtmaier C.1, Danninger H.1, Halvaci T.2, Weirather T.2, Granzer T.2
1TU Wien, Austria
2Plansee Composite Materials GmbH, Germany
Different commercial tungsten heavy alloys of the systems W-Ni-Fe, W-Ni-Cu and W-Ni-Fe-Mo were heat treated in the temperature range between 600 °C and 1260 °C to determine the resulting thermophysical, electrical and magnetic properties at ambient temperature. There is a clear trend of increasing saturation magnetization, thermal and electrical conductivity with decreasing heat treatment temperature. However, a surprising behaviour concerns the discrepancy between thermal conductivity calculated from electrical conductivity data via Wiedemann-Franz-law and direct thermal conductivity measurements; this needs further investigations.
To elucidate the influence of dissolved and precipitated tungsten in the binder, Fe-Ni-xW alloys with tungsten between 0 w% and 30 w% were prepared and their properties determined after the same heat treatments. Generally, the binder properties follow the same trend of increasing saturation magnetization with decreasing heat treatment temperature. The magnetization further increases with longer isothermal heat treatment at 1000 °C. This indicates that higher amounts of tungsten are dissolved at higher temperatures, whereas the precipitation of dissolved tungsten is responsible for the increase in saturation magnetization at lower temperatures.
RM 36
Interactions between Lattice Defects and Potassium Gas Bubbles in Doped Tungsten
Schade P.1
1HTM Consulting, Germany
From a historical as well as today’s point of view, doped tungsten is a unique material consisting of two non-alloyable elements, very high melting tungsten and low melting potassium.
Since the discovery of potassium gas bubbles about 50 years ago, the process understanding of the more than 100 years old P/M Coolidge technology has increased enormously, so that the tungsten technology can be considered as exemplary because it represents a significant materials science lesson on the mutual interaction between processing, microstructure, and materials properties.
However, some unexplained phenomena that have not yet been considered in detail, such as dynamic recovery and dynamic recrystallization during the manufacturing process as well as the behavior of bubbles at high temperatures, require still further investigations.
This paper focuses on the interaction between dislocations and potassium gas bubbles, pinning of low angle and high angle grain boundaries and detachment from bubbles as well as inhibition of the recovery behavior of doped tungsten, especially on a possible dragging mechanism of potassium gas bubbles through migrating grain boundaries. By comparing the calculated temperature dependence of a potassium bubble movement with measured fiber width growth rates in the temperature range T=1000°C…1900°C, it can be shown that for the occurrence of a retarded coupled migration of gas bubbles with fiber boundaries there exists a critical gas bubble radius r <= 10…15 nm. Through careful analysis of SEM and TEM images, the dragging mechanism could be observed in addition to the already known very strong pinning of longitudinal fiber boundaries by bubble rows.
RM 37
Processability of Nb-alloys
Van Steenberge N.1
1OCAS NV, Belgium
In this research the processability of Nb-alloys was investigated over the various steps of metal transformation, i.e. melting, shaping and heat treatment. Microstructural changes as well as oxygen content evolution were monitored over the different processing steps.
Small ingots of pure Nb and Nb-Hf-Ti (C103) were cast via vacuum arc melting (VAM).  These small-scale ingots were transformed successfully into sheets, via dedicated hot rolling trials.  Microstructural evaluation after hot rolling revealed that the microstructure was still fully “pancaked” and did not show any signs of recrystallization.  16 different heat treatments in the range of 700-1200°C, for time frames from 10 min up to 16 hours, have been performed.  The microstructural evolution upon recrystallization was followed via light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD).  A full recrystallization was only achieved at 1200°C.  Recrystallization textures evolves with temperature from an alpha-gamma fibre texture over a mixture of gamma and theta fibre towards a full theta fibre.
RM 38
On the phenomenon of 45° embrittlement in rolled tungsten sheets
Bonnekoh C.1, Lied P.1, Pantleon W.2, Hoffmann A.3, Reiser J.1, Rieth M.1
1Karlsruhe Institute of Technology, Germany
2Technical University of Denmark, Denmark
3Plansee SE, Austria
Tungsten sheets in as-rolled condition exhibit both, lower ductile-to-brittle transition temperatures and higher yield strength than their recrystallized counterparts. However, with increasing rolling deformation, these sheets are endangered by so-called 45° embrittlement, which is characterized by cleavage fracture showing a striking crack path of 45° regarding the rolling direction.
Here we show that 45° embrittlement needs to be comprehended as a combined effect of a high density of grains with rotated cube orientation and grain coarsening, whereby the latter can be observed in highly deformed tungsten sheets after very short annealings, e.g. by preheating between rolling passes. Rapid grain coarsening increases the spacing between grain boundaries along the crack front. This is interpreted as a reduction of possible sides of assisted nucleation of dislocations, which is considered primarily responsible for the increase in ductile-to-brittle transition temperature by 250 K to the as-rolled condition, thereby promoting brittle behavior. Due to the strong rolling texture, the preferred cleavage plane in most of the grains is aligned 45° to the rolling direction.
17:00 - 20:00
Poster Session Refractory Metals - Joining
Location: Poster Hall I
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RM 70
Research on TZM/graphite Joint Brazed without Pressure by Spark Plasma Sintering: Microstructure and mechanical properties
Han C.1, Sun D.1, Yang X.1, Zhang J.1
1Hefei University of Technology, China
The joint of TZM/graphite with Ti foil as the interlayer was successfully brazed quickly and without pressure by spark plasma sintering (SPS). The self-designed brazing fixture was used in the present study. The effect of brazing temperature on the properties of the joint was studied. The joint with the highest strength of 59 MPa was obtained when brazing temperature, holding time and interlayer thickness were 1580 ℃, 5 min and 200 μm, respectively. There were continuous TiC layer, finger-like TiC and (βTi, Mo) cross layer and (βTi, Mo) layer on the interface, and a small amount of TiC diffused into graphite through the pores which enhanced the strength of the joint. There was no cracks and unwelded areas at the interface. During the brazing process, recrystallization occurred in the TZM alloy, resulting in a decrease in its hardness and almost no anisotropy after brazed.
RM 71
Sinter-joining of W-10Ti powder to W-10Ti waste target by spark plasma sintering
Lei H.1, Yafei P.1, Jiuxing Z.1, Yong D.2
1Hefei University of Technology, China
2Central South University, China
SPS was used to sinter-joint W-10Ti powder and waste target at different temperatures and time to obtain the best process parameters for repairing W-10Ti target and explore the interface evolution mechanism. The results show that there are no holes or cracks on the interface at different temperature and time, and the hardness and density distributions near the interface are small. At 1200-1500 ℃, the grain size is close, and when the temperature rises to 1600 ℃, the grain size increases. In addition, the content of βTi(W) phase decreases with increasing temperature and time. Regenerated W-10ti targets with high density, less βTi(W) phase and smaller grain size can be obtained at 1500 °C and 5 min. EDSD results show that the diffusion of grain boundary induces the formation of wedge-shaped triple junction, and the reconstruction behavior occurs at the interface. In addition, a schematic diagram describing the mechanism of interface formation and evolution is established. It is considered that the sinter-joining process with SPS involves pressure welding, micro-arc welding, resistance welding and diffusion welding, etc.
RM 72
Characterization of laser welded molybdenum sheets
Hotz H.1, Rüttinger M.1, Lorich A.1, Kögl M.1, Schafbauer W.1, Knabl W.1
1Plansee SE, Austria
Joining molybdenum based materials by fusion welding causes a deterioration of mechanical properties due to local alterations of the microstructure. Sheets of pure molybdenum (Mo), as well as boron doped Mo (MoB15) and TZM were welded with the same process parameters to investigate the correlations between alloy composition and the process-induced changes in microstructure and mechanical properties. Furthermore, the impact of the laser power distribution and heat treatment after welding was investigated. For this purpose, room temperature tensile tests were carried out. The fracture surfaces were analyzed to determine the fracture mechanisms. The crack paths were investigated by means of microsections of the tested tensile specimens. The results show that intergranular fracture in the middle of the fusion zone is the overall most occurring failure. Recrystallization after laser welding can cause a shift towards cracks along the fusion line in Mo and into the base metal in TZM. MoB15 often exhibits transgranular cracks within the fusion zone, regardless of the heat treatment. The laser power distribution had no significant impact on the component properties.
RM 73
Optimization of Fusion Welding Processes for Molybdenum and TZM
Bölle S.1, Seiss M.2, Ruettinger M.3, Winkler J.3
1HS Kempten (Plansee SE), Germany
2Plansee SE, Germany
3Plansee SE, Austria
Bachelor thesis - abstract

Novel applications of refractory metals in semiconductor process equipment require components with complex shapes and designs and high mechanical strength. Their manufacturing process often comprises a fusion welding process step.

This work focusses on welded joints on sheet metal of pure molybdenum (Mo) and a molybdenum alloy with additions of titanium, zirconium, and carbon (TZM). First, the influence of the pre-welding cleaning process of the material is investigated. Second, various welding processes are compared, using tungsten inert gas (TIG) welding and laser beam welding. Third, the influence of a post-welding heat treatment is studied, varying the stress-relief annealing temperature. Specimens are analyzed by polished metallographic cross sections and tensile tests.

The results of this investigation will facilitate future design and manufacture of complex refractory metal components.
17:00 - 20:00
Poster Session Hard Materials - PVD Coatings
Location: Poster Hall I
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HM 65
Finite element analysis of WC-Co hard metal with microplane model and realistic FIB tomography meshes
Sousa Machado P.V.1, Caner F.1, Jimenez Pique E.1, Llanes L.1
1Universitat Politècnica de Catalunya, Spain
There has been great effort in modelling the behaviour of hard metals at microscale. However, the micromechanical data is usually inferred and the microstructure is generated by approximation. In this work, tomography images of the microstructure of the WC-Co are used to build realistic 3D meshes, then, with the microplane approach, finite element analysis is carried out in this microstructure. The microplane model, enforces the constitutive law at different planes within each material point, then imposes equilibrium between micro and macro stresses using the principle of virtual work. The results are compared with micropillar compression experiments. The constitutive relations are able to capture elastic, plastic and fracturing behaviour of each phase.
HM 66
On the Reduction of Computational Costs for Tungsten Powder Bed Processes
Estupinan Donoso A.A.1, Aminnia N.1, Peters B.1, Michels A.1
1University of Luxembourg, Luxembourg
During the Discrete Element Method (DEM) representation of powder bed processes (e.g. tungsten oxide reduction, tungsten carbide synthesis, selective laser sintering) a numerical solution for each single particle is impractical due to the extremely high number of particles (e.g. 10^12). However, in such processes, particles in the vicinity of each other observe low gradients concerning their thermodynamic state. This characteristic can be exploited to avoid solving repeatedly numerically equivalent equation systems.
This contribution presents two numerical methods aiming to reduce the computational costs of DEM approaches for the thermochemical conversion of powder beds. In the two methods after an appropriated numerical treatment, a group of particles under similar boundary conditions is substituted by a single-effective-entity. Consequently, the entire powder space is divided into sub-domains to be solved. The methods result in considerable lower number of equations that increase computational efficiency and enable feasible time simulations. The applications of the industrial synthesis of tungsten powders and the selective laser sintering (SLS) of powder metals are presented and discussed.
HM 67
FEM of stress partition during compression of WC-10 wt.% Co with realistic 3D morphology
Degeneve L.1, Mari D.1, Vinícius Sousa Madacho P.2, Jimenez-Piqué E.2
1EPFL, Switzerland
2UPC, Spain
A Finite Element Model is developed to represent the mechanical behavior of WC-10 wt.% Co in compression test. In this research, the realistic three-dimensional model is obtained by slicing a sample by Focused Ion Beam and reconstituting it, resulting in two interpenetrated phases. The brittle WC phase is defined as elastic. The Co phase includes plasticity. The post sintering cooling is simulated, followed by a loading-unloading compression cycle. The results are then compared with experimental data obtained by neutron diffraction. The thermal residual stresses in both phases are in good agreement with the experiment, featuring high tensile stress in the Co phase and moderate compressive stress in the WC phase. The elastic strain in the Co phase shows a good agreement in the loading cycle, but presents some differences in the unloading cycle. The plastic model applied to the Co phase is then modified to improve the accuracy of the simulation, showing a final good agreement with the experiment.
HM 68
TiN/TaN superlattice films improved by interfacial impurities
Gao Z.1, Buchinger J.1, Koutná N.1, Hazeu H.L.1, Koller M.1, Wojcik T.1, Bartosik M.2, Mayrhofer P.H.1
1TU Wien, Austria
2Montanuniversität Leoben, Austria
We obtained metastable rocksalt (rs) fcc-Ta0.5N with metal vacancies by DC reactive magnetron sputtering. As titanium nitride (TiN) and Ta0.5N have significant elastic differences and lattice mismatch, which promises a pronounced superlattice (SL) effect, TiN/Ta0.5N superlattice films were deposited on MgO (100) substrates, with a ~6 nm bilayer period. As expected, the SLs show a higher hardness (32.9 GPa) than monolithic Ta0.5N (30.1 GPa) and TiN (28.5 GPa), with an intermediate indentation modulus of 425.0 GPa (Ta0.5N 379.9 GPa and TiN 529.7 GPa).
As established by previous studies, the improved hardness is partly due to the hinderance of dislocation movement across interfaces. Thus, we attempt to implement atomic quantities of Si/C/B impurities in between all layers of TiN/Ta0.5N SLs to further enhance the interlayer boundaries. All of the TiN/X/Ta0.5N superlattice coatings show exceptional hardness properties and a near-epitaxial growth on MgO. Especially the TiN/Si/Ta0.5N films produced the highest hardness of 40.7 GPa. Overall, they possess promising hardness and stiffness and compare favorably to their monolithic building blocks and TiN/Ta0.5N SLs.
HM 69
Arc-evaporated Ti1-xAlxN coatings in Hot-Corrosion Settings
Hudak O.1, Scheiber A.1, Shang L.2, Hunold O.2, Arndt M.2, Kolozsvári S.3, Riedl H.1
1Christian Doppler Laboratory for Surface Engineering of high-performance Components, TU Wien, Austria
2Oerlikon Surface Solutions AG, Liechtenstein
3Plansee Composite Materials GmbH, Germany
Hot corrosion is a common phenomenon observed in gas turbine engines, coal gasification plants and waste incinerators. It occurs in high-temperature settings, where a sulfur-rich atmosphere reacts with salt impurities such as Na, Mg, Cl or V, and form high-melting sulfate-salts, that then deposit and adhere on machining component surfaces. There, the salt deposit elicits an accelerated degradation of the material through the formation of non-protective porous oxide scales. Depending on the temperature range, two distinctively different corrosion mechanisms can emerge. At temperatures below the melting point of the salt deposit (~600-850 °C), low-temperature hot corrosion dominates as mechanisms, whereas at temperatures above the melting point, high-temperature hot corrosion predominates (~850-950 °C). For all of the above mentioned fields of application, Ni-, Co-, and Fe-based superalloys have proven to be a reliable choice of material, due to their superior mechanical properties at high temperatures, as well as good oxidation resistance in air. However, if exposed to hot corrosion conditions, their overall oxidation resistant qualities diminish drastically.
From this perspective, this contribution showcases Ti1-xAlxN as an interesting candidate as protective PVD coatings for extending the lifetime of highly-stressed material components in hot-corrosion environments. Ti1-xAlxN coatings with varying metal content ratios were arc-evaporated on Ni-based superalloy substrates and tested in an in-house built hot-corrosion testing rig. By applying a sulphate-salt mixture from the alkali and alkaline earth metal group, the samples were corroded in a SOx-rich atmosphere for a maximum of 30 h according to the HTHC and LTHC conditions, and subsequently analyzed and evaluated for their applicability using a set of high-resolution characterization techniques.
HM 70
Microstructure and properties of duplex coating systems prepared by different PVD process parameters
Wüstefeld C.1, Motylenko M.1, Weinhold T.2, Dalke A.2, Sochora V.3, Biermann H.2, Rafaja D.1
1Institute of Materials Science, TU Bergakademie Freiberg, Germany
2Institute of Materials Engineering, TU Bergakademie, Germany
3SHM s.r.o., Šumperk, Czech Republic
The tribological resistance of forming tools can be improved by duplex surface engineering consisting of plasma nitriding of the steel substrate and a PVD process. In this study, plasma nitrided AISI D2 tool steel discs with and without a compound layer were used as substrates for the Cr-Al-Ti-B-N duplex coatings deposited using a hybrid PVD process combining cathodic arc evaporation and magnetron sputtering. The substrate pretreatment in the PVD process led to a thermal degradation of the compound layer. Thus, the parameters of the PVD process were adjusted to prevent the transformation of the compound layer to bcc-Fe. The samples were characterized by XRD, SEM, TEM, EPMA/WDX, scratch tests and nanoindentation, and were compared in terms of their chemical and phase composition, as well as macroscopic residual stresses, size and preferred orientation of fcc crystallites in the coating. The correlations between the microstructure characteristics, the parameters of the deposition process, the adhesion and the hardness are discussed.
HM 71
Fatigue crack growth resistance of a coarse-grained hardmetal grade
Serra Fanals M.1, García-Marro F.2, Konyashin I.3, Ries B.3, Llanes L.2
1Universitat Politècnica de Catalunya de Catalunya (UPC), Spain
2Universitat Politècnica de Catalunya, Spain
3Element Six GmbH, Germany
Attempting to optimize the performance and reliability of coarse cemented carbide grades, a testing program focused on the evaluation of crack growth resistance, under monotonic and cyclic loads, was conducted. Within this context, there are presented stable and unstable crack growth mechanisms evidenced during an extensive and systematic fractographic inspection of broken specimens, by means of Field-Emission Scanning Electron Microscopy combined with Focused Ion Beam milling, for coarse-grained WC-Co hardmetals. Aiming to analyze the fractographic transition discerned when moving from monotonic to cyclic loading, mean stress effects are also investigated by carrying out tests at different load ratios. Identification and predominance of fractographic features, such as ductile dimples, crystallographic-like steps or transgranular cleavage, are used for analyzing crack-microestructure interaction under different loading modes. Here, special attention is paid to specific scenarios linked to grain size and morphology as well as effective binder mean free path and/or carbide contiguity. Results are finally discussed in terms of prevalent toughening mechanisms developed during monotonic loading and how they get suppressed and/or degraded under variable loading conditions.
17:00 - 20:00
Poster Session Hard Materials - Materials
Location: Poster Hall I
Show all Abstracts
HM 52
Cemented medium-entropy carbides with Fe-based binder
Tarraste M.1, Pötschke J.2, Berger L.-M.2, Juhani K.1, Kübarsepp J.1
1Tallinn University of Technology, Estonia
2Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Germany
The (TiTaNbMoW)C high-entropy carbide (HEC) powder was prepared from the elemental powders of refractory elements and graphite by employing conventional ball milling and pressureless sintering. Synthesized HEC powder was milled with Fe and Fe-Mn to produce cemented carbides with HEC as hard-phase and ferrite (Fe) and austenite (Fe-Mn) as binder phases. Pressureless vacuum sintering and sinter-HIP were used for consolidation of HEC-Fe(Mn) composites. Synthesized HEC powder and sintered cemented carbides were subjected to the microstructural and phase characterization by means of SEM, EDS and XRD. The focus was on the phase changes that occur during sintering of HEC-Fe(Mn) cemented carbides.
HM 53
Effect of the binder on the sintering behaviour and mechanical properties of TiCN-Fe based cermets
Maurya H.s.1, Juhani K.1, Sergejev F.1, Viljus M.1
1Tallinn university of technology, Estonia
TiCN-Fe based cermets with various metallic binder contents were fabricated using a conventional powder metallurgy (PM) technique. This work aims to develop W, Co, and Ni-free cermets which is essential for developing cermets in the direction of green materials and technology. The effect of Cr, Mo, Si, Mn, and Nb on the sintering behavior, microstructure, and mechanical properties of the TiCN-Fe based cermet is studied and the cermet preparation process is optimized. Scanning Electron Microscopy (SEM) is employed to observe the microstructure, porosity, and crack propagation of cermets. The relative density, hardness, and fracture toughness are measured by the Archimedes principle, Vickers microhardness test, and indentation cracks propagation method respectively. The results show that the addition of Mo enhancing the densification of the cermets and strong carbide-forming element Nb serves to distribute Cr in the cermets evenly. The cermet based on Cr, Mo, and Nb binder has shown maximum hardness (1420 ± 39 MPa) whereas the highest fracture toughness achieved was 10.10 ± 0.8 MPa.m1/2 for the cermet based on Cr and Nb binder.
HM 54
Effects of zirconia on the mechanical properties and tribological performance of cemented carbides
Lu H.1, Jiang W.1, Jinghong C.1, Yulu Y.1, Xiaoyan S.1
1Beijing University of Technology, China
Yttria partially stabilized zirconia was introduced into WC-Co cemented carbides to enhance their mechanical performance. The hardness and fracture toughness were improved simultaneously with the addition of ZrO2. Particularly, the fracture toughness of the cemented carbides was significantly enhanced. The mechanism was mainly attributed to the stress-induced phase transformation of tetragonal ZrO2 to monoclinic ZrO2. This phase transformation introduced a compressive stress field and avoided the stress concentration, hence reduced the plastic deformation and deflected the micro-cracks. In addition, the ZrO2 particles had good interfacial bonding with the WC phase, which allowed lattice strain matching and effective load transfer between the two components, thus beneficial to the mechanical properties of the cemented carbides. The phase transformation of ZrO2 also contributed to the improvement in the wear resistance of cemented carbides. This study provides a new promising approach to achieve excellent comprehensive mechanical properties for cemented carbides.
HM 55
Thermal conductivity of WC-Co with modified binder
Eso O.1, Comar A.1, Bitler J.1
1Kennametal Inc., USA
The thermal conductivity of WC-Co is one of the predictors of its thermal cracking resistance. Thermal cracking resistance of WC-Co tends to increase with fracture toughness. Thermal conductivity of WC-Co decreases with dissolved tungsten in the binder phase. Some alloying elements can alter the binder chemistry of WC-Co by dissolving in the cobalt phase during sintering, resulting in a composite with improved the fracture toughness and wear resistance combination. An understanding of the effect of binder phase chemistry modification by alloying on the thermal conductivity of WC-Co is lacking. This study investigates the effect of doping on the thermal conductivity of WC-Co.
HM 56
Microstructure, Mechanical and Mössbauer Characterisation of Fe and Ni bonded NbC cermets
Peters G.1, Naidoo D.1, Genga R.1, Freemantle C.2
1University of the Witwatersrand, South Africa
2Pilot Tools (Pty) Ltd, South Africa
NbC cermets with Fe and Ni binders have been vacuum sintered with molybdenum carbide additives. The magnetic, electrical and thermal properties have been investigated using Mӧssbauer spectroscopy and a Physical Property Measuring System. The addition of 4wt% molybdenum carbide to the Fe and Ni binder grades shows an average increase of 12% in the hardness of the cermets with little compromise in the fracture toughness property. The Mössbauer spectrum shows the presence of ferromagnetic phases in the binder of the NbC-12Fe grade. The binder of the NbC-12FeNi spectrum is dominated by a paramagnetic phase with a minor ferromagnetic phase. The addition of molybdenum carbide to NbC-FeNi results in a completely paramagnetic structure which is most likely gamma-FeNi as compared to NbC-Fe where the spectrum is dominated by ferromagnetic behaviour. X-ray diffraction (XRD) in combination with high resolution scanning electron microscopy (SEM), Transmission electron Microscopy (TEM) and Annular Dark field (ADF) Scanning Transmission Electron Microscopy (STEM) data will be presented to corroborate results from Mössbauer Spectroscopy.
HM 57
Wetting behavior comparison of liquid equiatomic FeCoCrNi and CoCrNi on binderless TiC0.7N0.3 substrate
Liu T.1, Zhang L.1, Huang B.1, Zhu J.-f.1, Liu Z.-m.1
1State Key Laboratory of Powder Metallurgy, Central South University, China
Functioned as the binder metal, medium-entropy (MEA) and high-entropy alloy (HEA) with high toughness and strength can be a solution for the toughness improvement of cermets. To explore the feasibility, contact angle evolutions between liquid equiatomic CoCrNi/FeCoCrNi alloy and binderless TiC0.7N0.3 substrate were tested by a sessile drop method. The results show that for CoCrNi and FeCoCrNi, the initial contact angles and the corresponding complete melting temperatures are 25.4° (1389 °C) and 28.8° (1392 °C), respectively. Ti and C atoms in the substrate can diffuse into the (Fe)CoCrNi-layer. (Fe)CoCrNi presents a gradient variation in the substrate. No reaction layer at the interface is identified. Accordingly, wetting of these alloy system is driven by a dissolution- and diffusion-driven mechanism. The wetting behavior confirms that (Fe)CoCrNi can be a good candidate for the binder metal. Compared with FeCoCrNi, melted CoCrNi exhibits a relatively stronger infiltration and diffusion ability in the substrate, and hence more suitable for TiCN-based cermets. Our results can shed light on the composition and technique designs of TiCN cermets.
HM 58
The effect of Ni and Co binder ratio on the microstructure and phase evolution of WC modified NbC based cermets
Huang J.1, Shuigen H.1, Peng Z.2, Bert L.1, Jun Q.1, Jef V.1
1KU Leuven, Belgium
2Hunan University of Science and Technology, China
In this study, the influence of different Co contents in a 10 vol% (Ni-Co) binder on the microstructure and phase evolution of 7.5 vol% WC modified NbC based cermets, prepared by pressureless liquid phase sintering in vacuum for 90 min at 1390°C was assessed. Microstructure and phase analysis using SEM and XRD  indicated that the WC modified NbC based cermets were composed of a (Nb,W)C solid solution cubic phase dispersed in a Ni-Co alloy binder with ≤ 5 vol% Co, whereas eta phase was present at ≥7.5 vol% Co. With increasing C content addition, the eta phase was transformed into WC and the (Nb,W)C grain shape changed from angular to round in the carbon-rich NbC-10Co-7.5WC (vol%) powder based cermets. The phase and grain shape evolution with different Co or C content was discussed and the fracture toughness, Vickers hardness and transverse rupture strength was assessed.
HM 59
Tailoring microstructure and mechanical properties of NbC-Ni matrix cermets for wear resistance applications
Huang s.1, Liu C.2, Liu B.2, Vleugels J.1, Huang J.1, Anwer Z.1, Lauwers B.1, Qian J.1, Cannizza E.3, Woydt M.4
1KU Leuven, Belgium
2Xiamen Tungsten Co., Ltd, China
3EHT-Engineering Consulting Ltd, Brazil
4MATRILUB, Germany
NbC-Ni based cermets were prepared by conventional liquid phase sintering in vacuum above 1390°C. The influence of the Ni binder content, additions of carbides (Mo2C, WC, VC and TiC) and Ti(C0.7N0.3) on the microstructure and mechanical properties of NbC based cermets were investigated. Results indicated that the partial replacement of NbC by the additions had a significant effect on the NbC grain growth and properties of fully densified NbC-Ni based cermets. The microstructure of the novel NbC cermets can be tailored via secondary carbide or carbonitride additions, i.e. a WC-Co like microstructure in the single carbide (VC or Mo/Mo2C) modified cermets and a Ti(C,N) cermet like microstructure with core-rim NbC solid solution grains with additional Ti(C,N) addition. The NbC-Ni based cermets exhibit a room temperature HV30 hardness of 900 to 1600 kg/mm2, a Palmqvist indentation toughness of 7 to 15 MPa m1/2, and a flexural strength of 1500-2300 MPa. Depending on the property combination, different wear resistant applications, such as wear parts and cutting inserts are explored and compared to WC-Co materials.
HM 60
Study of hardness gradient in functionally gradient cemented carbides developed through a novel technique
Shenoy C.1, Shetty S.1, Kumar SN B.1, Shanmugam N.1, Shadakshari S.1, Karthik V.1
1Kennametal India Limited, India
Commercial functionally graded materials in cemented carbides are available with hardness gradient primarily driven by the binder content and cubic carbide content. These FGMs are reported to have a maximum gradient layer thickness of 50 microns from the surface and predominantly achieved during sintering stage with a gradient in carbon, nitrogen or oxygen. However In this study, gradient layer is achieved in cemented tungsten carbide by creating compositional gradients. Different factors, which can be used to influence the diffusion of metallic species dissociated from the cubic carbides in cobalt binder phase during sintering are investigated. These factors include gradients in cubic carbides, grain size, carbon and cobalt content. Also the effect of these compositional gradients on hardness and microstructure are studied and discussed.
HM 61
Effect of nitrogen content on microstructure and mechanical properties of NbC-WC-Ti(C,N)-Ni cermets
Huang S.1, Liu C.2, Liu B.2, Vleugels J.1, Huang J.1, Anwer Z.1, Lauwers B.1, Qian J.1
1KU Leuven, Belgium
2Xiamen Tungsten Co., Ltd, China
This study investigates the influence of the nitrogen content on the microstructure and room temperature mechanical properties of NbC based cermets, i.e. NbC-9Ni-24WC-14Ti(C,N) (wt%). The Ti(C,N) refers to either TiC, Ti(C0.7N0.3) or Ti(C0.5N0.5). All cermets were prepared by pressureless liquid phase sintering in vacuum for 90 min at 1450°C. Detailed microstructural investigation was performed by SEM, EPMA and XRD analysis and the sintered phase constitution was compared with thermodynamic modelling predictions. The sintering results indicated that a variation in N content had a significant effect on the grain growth of the in-situ formed NbC solution carbide and fracture toughness of the cermets. The NbC cermets were composed of a fcc solid solution metallic binder and a cubic core-rim (Nb,Me)(C,N) solution phase. The observed phase constitution of the cermets and change in lattice parameters of the observed phases were supported by thermodynamic equilibrium calculations. A good combination of Vickers hardness (HV30) 1500 ~ 1600 kg/mm2 and indentation toughness of 8 ~ 9 MPa.m1/2 were obtained in the NbC matrix cermets.
17:00 - 20:00
Poster Session Refractory Metals - Powders and sintering
Location: Poster Hall I
Show all Abstracts
RM 57
A novel de-oxidation method for Mo powder by low temperature reaction
Wang X.Q.1, Zuo Y.F.1, Luo J.H.1
1Jinduicheng Molybdenum Co.,LTD, China
Oxidation on the metal powder surface is a major challenge to molybdenum metallurgy. A new de-oxidation method of Mo powder was explored based on the types of oxides on powder surface determined by XPS analysis. Corresponding reduction process was designed and the hydrogen dew-point control combined with a temperature profile of 400~680℃ resulted in powder with oxygen less than 400ppm, minimum 250ppm with low cost. The low oxygen powder retained the original Mo morphology of individual particles .
RM 58
A Metallurgical Approach to the Zinc-Reclaim of W/Cu Composites
Edtmaier C.1, Schubert W.-D.1, Weissensteiner C.1, Zimmerl T.2, Mühlbauer G.2, Qvick J.3
1TU Wien, Austria
2Wolfram Bergbau- und Hütten AG, Austria
3Seco Tools AB, Sweden
Tungsten recycling has a longstanding tradition due to economic reasons and particular shortfall of resources. Tungsten also belongs to the list of critical raw materials (CRMs). W/Cu is actually technologically not considered by the industry, as it neither can be processed into the steel industry, nor direct into the tungsten primary production cycle. A typical industrially used method is Zinc-Reclaim, which is a well-established technological process for recycling of hardmetals, but currently not applied for the recovery of W/Cu composites. The aim of these experimental investigations is to identify reactions and their kinetics between molten Zn and solid Cu binder. Different Zn-containing phases are formed depending on processing conditions like time, temperature and the Cu:Zn ratio. It is shown that the temperature dependency of solubility of binder metals in the Zn-melt influences the process. During Zn treatment, the microstructure of the W/Cu composites is completely disintegrated by the formation of solid Zn-containing phases. After distillation of the Zn, the remaining disintegrated W/Cu composite powder can be easily reused for the preparation of new composite parts.
RM 59
Reactive Sintered Tungsten Borides: Determining Optimum Processing Conditions
Marshall J.1, Humphry-Baker S.2, Smith G.3, Astbury J.4
1University of Warwick, United Kingdom
2Imperial College London, United Kingdom
3University of Oxford, United Kingdom
4Tokamak Energy, United Kingdom
Reactive Sintered Borides (RSBs) are a new class of tungsten borides and iron tungsten borides-rich hardmetals ( ≥ 30 at% B)  developed from cemented tungsten carbides (cWCs). RSBs are of particular interest as low-activation compact neutron absorbing materials, having mechanical properties similar to cWCs and can be processed using conventional powder metallurgy.
All RSB materials to date have been processed using  cWC processing routes, but these are not optimal for dense, pore-free RSB materials. This work investigates organic binder removal, consolidation and initial phase formation in a selection of RSB compositions alongside cWCs using differential thermal analysis (DTA), thermal gravimetric analysis (TGA) and mass spectrometry.
Phase formation and gas evolution from cWC and RSB materials with polyethylene glycol (PEG) up to 1100°C was investigated in this study. Peak gas evolution was shifted from 370°C to 330°C for cWCs and RSBs respectively. H2 outgassing was greater for RSBs than cWCs over a wider temperature range. More dwells are required for RSBs to ensure full densification relative to cWCs.
17:00 - 20:00
Poster Session Refractory Metals - Characterization and simulation
Location: Poster Hall I
Show all Abstracts
RM 74
On the preparation of W-Re conversion layers for high resolution electron microscopy based studies
Sommerauer M.1, Siller M.2, Clemens H.1, Maier-Kiener V.1
1Montanuniversität Leoben, Austria
2Plansee SE, Austria
WRe-alloys, used as conversion layers in rotating anodes, experience microstructural changes, cracking and other signs of fatigue. This fatigue is introduced by the thermomechanical loading during computed tomography operation. Various electron microscopy techniques can be utilized to assess these phenomena.
In order to achieve satisfactory results especially in terms of image quality and prevention of artefacts from preparation, multiple steps during sample preparation (grinding, coating, conventional and electro-chemical polishing, ion-slicing, etc.) have to be taken. This work aims to compare different preparation methods to improve achievable image quality, while considering time expenditure and cost.
The adequacy of the methods was evaluated based on the visibility of the cracks on the cross-section samples.
In addition, the degree of surface disruption caused by the different preparation approaches was compared to minimize the material loss, and therefore information loss, caused by these methods.
These results, amongst others, show, that applying a thin coating of Molybdenum on the sample surface could drastically decrease the degree of surface disruption. This allows for more accurate analysis of the conversion layer fatigue.
RM 75
Overview of Southern Research Testing Capabilities new
Wood J.1
1Southern Research, USA
Southern Research (SR), a not-for-profit research institute in Birmingham, AL, USA, is known worldwide for their expertise in high temperature testing of materials.  With capabilities in a variety of mechanical, thermal, and non-destructive property evaluation, SR can provide a full suite of property measurements over a wide range of temperatures.  Test temperatures range from -269C to 2760C to meet a wide variety of applications.

Key mechanical test capabilities include tension, compression, torsion, flexure, fatigue, and creep.  Thermal test capabilities include thermal expansion, thermal conductivity, specific heat capacity, and thermal diffusivity. Specialized testing capabilities include emissivity, permeability, and dielectric properties over various temperature ranges.  Custom test development and techniques are also available.

SR has developed specific testing expertise and processes for testing refractory metals at elevated temperatures in air, inert, vacuum, and partial pressures.  An overview of SR’s testing capabilities specific to refractory metals will be presented.
RM 76
Determining high temperature flow curves of refractory metals from dilatometer tests by using inverse simulation approach
Rothenbucher G.1, Loidolt P.1
1Plansee SE, Austria
High temperature uniaxial compression tests of refractory metals are significantly influenced by friction at the contact surfaces between the specimen and upsetting tools.
Due to friction induced barrelling of the specimen the common assumption of a homogenous stress and stain distribution over the cross section of the specimen is no longer valid.

The friction induced effects can be considered in a combined experimental and numerical methodology, from which the actual high temperature flow curves are determined.

I.e., the actual flow curves are derived by an automated iterative process aligning deformations and forces computed with finite element models to experimental compression test results.
RM 77
Uranium in Tungsten Metal Powder Measurement by GDMS
Chau C.1
One of the purity requirements for the use of Tungsten in electronic components is Thorium <0.1 ppb and Uranium <1 ppb. Since Thorium and Uranium are common contaminants in most tungsten ores, the specification of a low level of Th and U is necessary to ensure minimal radioactive interference from the Tungsten components. Measurement of such low levels of Thorium and Uranium can be performed routinely with the Glow Discharge Mass Spectrometer (GDMS) technique. This paper describes how a standard for this measurement is calibrated at GTP. Thorium extraction from tungsten ore is generally efficient and achieving a 0.1 ppb level measurement is not a complicated process. Uranium, on the other hand, tends to remain with the Tungsten during the extraction process. Therefore, it is necessary to have a reliable quantification method for the determination of Uranium in Tungsten. We measure the Uranium in Tungsten metal powder using Radiochemistry. Using a calibrated standard, we have established the true relative sensitivity factor (RSF) for Uranium in tungsten metal powder for GDMS quantitative measurements.
RM 78
A Reheating Time Optimizer for Refractory Metal Plates in Batch-Type Furnaces
Rötzer F.1, Aschauer A.2, Steinboeck A.2, Reichl G.3, Eidenberger-Schober M.3, Kugi A.2
1AIT - Austrian Institute of Technology, Austria
2TU Wien, Austria
3Plansee, Austria
A method for reliable, data-driven real-time optimization of reheating times of refractory metal plates in a batch-type furnace is presented. The considered furnace is part of a hot rolling plant for heavy plates and thin sheets. The furnace temperature is controlled to a constant setpoint and the product temperature evolves asymptotically. Consequently, the sensitivity of the required reheating time with respect to the desired discharge temperature strongly increases towards the end of a reheating cycle.
A mathematical model of the reheating process with a minimal number of parameters is developed for the optimization of the reheating times. The unknown parameters are repeatedly estimated and updated based on the product temperatures recorded during charge and discharge events. Similar products are grouped and the parameter estimates and reheating times are calculated per group.
The developed method is tested on a finite-volume simulation model of the furnace, assuming perturbed parameters to analyze its accuracy and robustness. The numerical results show that highly accurate results for parameters and optimal reheating times can be achieved at low computational costs.
RM 81
DFT calculations on BCC-based ordered or disordered Mo-Ti binary alloys new
Kaneko T.1, Yoshimi K.1
1Tohoku University, Japan
This study used density functional theory calculations to investigate the basic properties (formation
enthalpy, lattice parameter, and elastic modulus) of a Mo-Ti binary BCC structure. Based on the results
of formation enthalpy calculations, the most stable structures in the range of xTi < 25 at.% were obtained
when the distance between the nearest-neighbor Ti-Ti was the third-nearest neighbor in the BCC
structure. Disordered structures were stable above xTi = 25 at.%; consequently, the most stable
structure in the range of 0 < xTi < 50 at.% was the D03 ordered structure (xTi = 25 at.%). Additionally, the
atomic arrangement also affected the atomic volumes of Mo and Ti within a structure. A Bader charge
analysis revealed the atomic volume of Ti to be almost constant in the range of xTi ≤ 25 at.%.
Conversely, the atomic volume of Ti increased with an increase in the Ti content in the range of xTi > 25
at.%. The atomic volume of Mo increased monotonically with an increase in the Ti content. For this
reason, the lattice parameter of the Mo-Ti-based BCC structure does not obey Vegard’s law. The
calculation result for the bulk and shear moduli of Mo-Ti revealed that both elastic moduli decreased with
an increase in the Ti content in the range of xTi < 50 at.%. Furthermore, the change in the elastic
modulus of the Mo-Ti-based BCC structure corresponded to the change in the electronic density of
states according to Ti composition.
17:00 - 20:00
Poster Session Refractory Metals - Applications
Location: Poster Hall I
Show all Abstracts
RM 39
Optimization of doped lanthanated tungsten components in ion sources by determining the temperature profile for halogen processes
Schaper F.1, Schulz S.2, Leitz K.-H.3, Winkler J.3
1Plansee Electro-Graph, USA
2Infineon Dresden, Germany
3Plansee Reutte, Austria
Aggressive environments like fluorinated source gases lead to erosion and wear (halogen cycle) in ion implant equipment. Lanthanated tungsten (WL) has been commonly used in these applications, primarily in ion implant sources. Especially the process gas GeF4 contains halogen compounds and produces a large amount of free fluorine radicals. The present work involves the practical and theoretical evaluation of a realistic, in-situ process temperature profile of an ion source equipped with WL liners. Hereby a GeF4 environment was investigated to confirm the functionality of WL materials at elevated temperatures above 1000°C. The two routes chosen in this work are a practical approach on one hand. An ion source was redesigned to hold up to 2 modified ceramic tabs to produce data sets that are used to define the exposed plasma temperature. On the other hand, a finite element simulation of an ion source was established. Both results are finally compared to create a realistic statement regarding the temperature profile. The aim is to get a deep understanding of the behavior of WL in fluorine-rich plasma's.
RM 40
Novel manufacturing methods of rotor bodies using cold gas spraying
Bienert C.1, O'Sullivan M.1, Wagner J.1, Lang B.1, Sprenger D.1
1Plansee SE, Austria
Plansee provides numerous different parts for vacuum technology and x-ray technology systems, for example rotating anodes or components for gear. In addition to traditional production techniques, new methods of production come into focus to improve and develop product properties for a broad variety of applications. Cold gas spraying (CGS) is one example of an innovative method for additive manufacturing. Rotor bodies are interesting candidates for applying copper via CGS instead of using traditional backcasting or brazing. Thus, a higher electrical conductivity and the elimination of intermetallic phases can be achieved for the interface region. In a systematic approach we studied the influence of relevant process parameters as well as dependencies on raw powder material and surface treatment prior to coating. Furthermore, the different spraying parameters and their resulting layer formation is discussed. Evaluation of the deposited copper layers is then done by measuring their adherence on the steel body. The prototypes were tested for the electrical conductivity which can be further increased by applying a post-manufacture heat treatment.
RM 41
Feedback during series fabrication of ITER like divertor Tungsten components for the WEST tokamak
Lipa M.1, Firdaouss M.1, Li Q.2, Luo G.2, Missirlian M.1, Richou M.1, Wang W.2
1CEA, IRFM, France
2Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), China
The purpose of the WEST-Tokamak is to test key technologies for future fusion devices like ITER. In particular the actively cooled plasma facing units (PFU), using the so-called tungsten-monoblock (MB) technology, has been installed on the WEST lower divertor, allowing studies and analyses of the plasma wall interaction. 456 of such W-plasma-facing units have been manufactured during the last years, using hot isostatic pressing (HIP) as main assembly process. The manufacturer of the PFUs was the Chinese company AT&M, with the assistance of an expert team from ASIPP. The production started in December 2018, and the last batch was delivered to CEA/IRFM in October 2020. Besides some issues during fabrication, main requirements have been reached. The key production steps, as well as the associated controls and tests are described.
RM 43
Natural ageing and phase changes in biomedical Zr-Nb alloys: a ten years follow-up
Gasik M.1, Ashida M.2, Hanawa T.2
1Aalto University School of Chemical Engineering, Finland
2Tokyo Medical and Dental University, Japan
Alloys based on Zr-Nb system have been developed for use of medical implants and instrumentation due their lower elastic modulus and magnetic susceptibility, which is important for quality MRI imaging. This system is known for a variety of slow and metastable transformations and different phases which can substantially deteriorate properties of the materials.
In this work we investigated Zr-(16-20)%Nb alloys by simultaneous thermal analysis, XRD and microscopy and compared the data for cast and naturally aged alloys after 5 and 10 years. The identified phase transformations including alpha, β" and ω phases and decrease of primary β-phase were different for fresh and aged alloys, but the constitution of these phases was not affected by over 10 years ageing. The effect of long-time ageing phase transformations in the Zr-Nb system are discussed and compared with literature data for shorter ageing times.
RM 44
Electron emitting C12A7-Mo composites with improved electronic, thermal and mechanical properties
Wätzig K.1, Schilm J.2, Drobny C.3, Tajmar M.3, Kusnezoff M.2
1Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Germany
2Fraunhofer Institute for Ceramic Technologies and Systems, Germany
3Technische Universität Dresden, Germany
Electron-emitting materials are applied in electron sources for e. g. space propulsion of satellites and X-ray detection. The ceramic material [Ca12Al14O31]4+4e- (named as C12A7) is providing a low-work function of < 2.4 eV. Therefore, a considerable current density can be measured below a temperature of 1000 °C in vacuum [1]. Although the material is suitable as an electron emitter with its low work function and sufficient electrical conductivity, it degrades in long-term applications due to low thermal conductivity and poor mechanical properties [2].
In our investigations, we overcome these disadvantages by mixing C12A7 and Mo metal to prepare a C12A7-Mo composite. The thermal and mechanical properties of the composites as function of the Mo content were characterized. Additionally, the electron emission of the composite material in a low-temperature, heaterless hollow cathode was characterized.
The improved mechanical and thermal properties of the composites are enhancing the long-term performance of the cathode for continuous electron emission under moderate conditions.

[1] A. Heiler, K. Waetzig, M. Tajmar, et al.
[2] K. Waetzig, J. Schilm.
RM 45
A Faster Route to Fusion: The Critical Role of Tungsten-based Materials in Compact Reactors
Smith G.1, Astbury J.2, Humphry-Baker S.3, Marshall J.4, Morgan G.5, Windsor C.2
1Tokamak Energy and University of Oxford, United Kingdom
2Tokamak Energy, United Kingdom
3Imperial College London, United Kingdom
4University of Warwick, United Kingdom
5Culham Electromagnetics, United Kingdom
Compact tokamak reactors present an exciting new route to commercial fusion energy.  Their small size and flexible design allow rapid, agile and cost-effective development, with a high degree of innovation at every stage.  The Spherical Tokamak (ST) design allows particularly efficient use of the magnetic field for plasma confinement, good plasma stability, and a low overhead in terms of energy consumption during operation compared with conventional tokamaks.  The compact design means that maximally efficient radiation shielding of the superconducting magnet coils is of critical importance.  Tungsten carbide- and tungsten boride-based materials prove to be optimum for this purpose.  Tungsten carbide-based materials are also relevant for other reactor components, including the divertor and first wall.  We provide a short overview of our programme of work on the development of these materials for fusion engineering applications, including key aspects of materials processing, characterisation and property measurements.
RM 46
Comparison of K-doped and pure cold-rolled tungsten sheets: Microstructure restoration in different temperature regimes
Lied P.1, Pantleon W.2, Bonnekoh C.1, Dürrschnabel M.1, Bienert C.3, Hoffmann A.3, Reiser J.1, Rieth M.1
1Karlsruhe Institute of Technology (KIT), Germany
2Technical University of Denmark, Denmark
3Plansee SE, Austria
For tungsten in divertor parts of future fusion reactors, a fine-grained microstructure is preferred to reduce its brittle-to-ductile transition temperature and minimize cracking events due to cyclic thermal and mechanical loading. In our ongoing study on tungsten sheets with different degree of deformation by warm- and cold-rolling, the potential of potassium-doping to stabilize the microstructure at high operation temperatures is assessed. Successful production of technically pure and equivalently rolled potassium-doped tungsten sheets up to very high logarithmic strains of 4.6 was already shown in the past with in-depth analysis of the evolution of microstructure and mechanical properties after rolling steps. Our current study investigates the microstructure changes in the same material batch by recovery, recrystallization and grain growth in temperature regimes between 600 °C and 2400 °C. Annealing studies with subsequent microhardness and SEM analysis reveal increased retardation of recrystallization in potassium-doped tungsten with higher rolling-strain, but abnormal grain growth at high temperatures is also increased. However, potassium-doped tungsten with low rolling-strain shows promising results with much less grain growth than its pure tungsten counterpart.
17:00 - 20:00
Poster Session Hard Materials - SIS on 3D printing
Location: Poster Hall I
Show all Abstracts
HM 140
Testing length-scale considerations in mechanical characterization of WC-Co hardmetal consolidated by binder jetting additive manufacturing
Cabezas L.1, Berger C.2, Roa J.J.1, Jimenez-Piqué E.1, Pötschke J.2, Llanes L.1
1CIEFMA - Department of Materials Science and Engineering, EEBE - Polytechnic University of Catalonia (UPC), Spain
2Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Germany
The extreme versatility of additive manufacturing (AM) as processing technology results in “AMed pieces” with intrinsic characteristics linked to the shaping route followed, which are also vital for defining structural integrity. Moreover, the fact that AM techniques enable microstructure control at discrete physical voxels through a part volume, it implies that defects  could also subsequently being introduced at similar length scales. Hence, mechanical integrity for AMed materials requires validation by measuring the mechanical properties, both globally (macromechanically) and locally (micromechanically). This work aims to study the correlation among microstructure, layer assemblage (directly linked to printing orientation) and mechanical properties – mainly hardness and crack resistance - at different length scales for a 12%wtCo–WC hardmetal grade consolidated by binder jetting AM. Besides macro- and micro- Vickers hardness, small-scale Berkovich hardness and elastic modulus are assessed as mechanical property maps, by means of high speed massive nanoindentation. The results are analyzed and discussed in terms of oriented layer-like material assemblage and microstructural scenario (including possible heterogeneities), intrinsic to material (physical) deposition (printing) processes and feedstock used respectively.
HM 141
Surface integrity at the nanometric length scale of 3D printed WC-Co under service-like working conditions
Riu Perdrix G.1, Weil D.2, Johanns K.3, Oliver W.C.3, Roa Rovira J.J.1
2KLA-Tencor GmbH, Germany
3KLA Corporation, USA
Cemented carbides are heterogeneous composite materials used as tools and/or components within a broad range of industrial applications with stringent demands.
In particular this presentation is focused on WC-Co hardmetals as reference hard material. A large number of studies have been reported on the mechanical behavior of this composite. However, information on the small-scale high temperature mechanical response of 3D printed specimens is rather scarce.
Within this context, the main goal is to evaluate and correlate the surface integrity in terms of mechanical properties at different temperatures from room up to service-like working conditions as a function of the microstructure and the printing direction at the submicrometric length scale prepared by using the DryLyte® technology. Preliminary results, highlight a clear correlation between local mechanical property and the printing direction.
17:00 - 20:00
Poster Session Hard Materials - Characterization and testing
Location: Poster Hall I
Show all Abstracts
HM 126
Thermal-mechanical properties of binderless WC in extreme environments
Humphry-Baker S.1, Currie B.1, Smith G.2, Mellan T.1, Salvatore G.3, Pintsuk G.4, Polcik P.5
1Imperial College, United Kingdom
2Tokamak Energy Ltd, United Kingdom
3Southwest Jiatong University, China
4Forschungszentrum Juelich GmbH, Germany
5Plansee Composite Materials GmbH, Germany
Binderless WC shows promise for applications in high temperature machining and compact neutron shielding. However its thermal-mechanical properties above 1000°C are poorly characterised. We report creep and fracture data up to 2000°C, thus substantially expanding previous work. We observe a transition from diffusional to power-law creep – as evidenced by changes in the stress-exponent and deformation texture – at ~1500°C. This temperature coincides with a brittle-to-ductile transition and a peak in fracture strength, which for sub-micron grain size materials approaches 1.8 GPa. Systematic thermal conductivity data is also presented. Previous literature shows that conductivity depends heavily on carbon content and the results were explained by so-called “graphitic nanolayers”. Here we show the effect is, instead, explained by grain size and porosity variation. Our interpretation is supported by thermal transport simulations. Finally, we report the response to plasma instabilities (thermal shock events) by applying 1 ms electron beam pulses up to ~1GW/m2. The material outperforms unreinforced metallic tungsten, suggesting it as a candidate plasma-facing material. Strategies for further material development are discussed.
HM 127
Comparison of high-temperature tribological properties in different high-entropy sublattice ceramics
Kretschmer A.1, Rojacz H.2, Badisch E.2, Mayrhofer P.H.1
1TU Wien, Austria
2AC2T Research GmbH, Austria
High-entropy sublattice ceramics are promising candidates for application as wear resistant thin films. Therefore, the tribological performance of three different sputtered high-entropy sublattice ceramic coatings, (Al,Cr,Nb,Ta,Ti)O2, (Al,Cr,Nb,Ta,Ti)N, and (Hf,Ta,V,W,Zr)B2, with excellent thermal stability up to 1200 °C and as-deposited hardness values of 24, 32, and 45 GPa, respectively, was analyzed and compared against TiN in dry pin-on-disk tests at room temperature (RT), 400 °C, and 700 °C, and in high temperature (HT) scratch tests. In the dry pin-on-disk tests all coatings show similar coefficients of friction (CoF) around 0.8-1.0 at RT. The oxide coating exhibits a CoF below 0.2 at 400 °C, but suffers quick delamination at 700 °C. The CoF of (Al,Cr,Nb,Ta,Ti)N and TiN at 700 °C decreases to ~0.4 after a run-in phase, while the boride shows the opposite behavior, peaking at ~1.3. The stability in the wear tests strongly relies on the mechanical behavior of the coatings at different temperatures and can be correlated with the critical loads obtained in the HT scratch tests.
HM 128
Archard wear coefficient (k) determination and its relationship with microstructure and load applied throughout scratch tests– Experimental and Numerical approach
Lima A.1, Martins de Souza R.1, Machado I.1
1University of São Paulo, Brazil
Abrasion is one of the wear mechanisms that limits the lifespan of hot working tools. The Archard equation is frequently used to quantify the abrasive wear based on wear coefficient (k). This work addresses to determine Archard wear coefficient in a complex microstructure of a type cast iron using experimental and numerical methods, respectively. Experimentally, the abrasion wear was evaluated throughout a ramp-load scratch tests (50 mN and 100 mN of maximum loads) using the triboindenter Hysitron Ti-950, Bruker Inc. A diamond conospherical tip with with 10 µm diameter was used. The microstructural and wear track characterization were conducted using optical and scanning electron microscopy. In addition, the numerical model was developed using Abaqus® software. In the numerical model, the k determination considered the maximum depth of the scratch and the different microstructural features, such as phase size and distribution. The numerical results were corroborated by experimental results.
HM 129
Thermal properties of cemented carbides used for metal cutting
Kazymyrovych V.1, Kryzhanivskyy V.1
1Seco Tools AB, Sweden
High temperatures, generated during machining, may have a detrimental effect on the cutting tool. Therefore, tool material’s ability to effectively lead away the heat is an important property that needs to be understood and quantified. To achieve that, thermal conductivity, diffusivity and specific heat of 20 cemented carbide grades were studied using light flash analysis at temperatures between 22 and 800 ℃.
The results demonstrate how thermal conductivity of cemented carbides increases with coarser WC grain size and lower Co content. Presence of cubic carbides in the material is shown to greatly reduce its thermal conductivity. Specific heat of investigated materials increases with higher Co and cubic carbides content, but it is not affected by WC grain size. Influences of temperature on thermal properties are illustrated and discussed.
Most importantly, using regression analysis, an attempt is made to predict thermal conductivity based on reliable, readily available or easily measurable material characteristics. It is shown that thermal conductivity of cemented carbide grades could be estimated with good accuracy from the material’s chemical composition and coercivity value.
HM 130
Implementation of laser ablation techniques to introduce effective notches for reliable assessment of fracture toughness of hardmetals
Ortiz Membrado L.1, Liu C.2, Prada J.3, Jiménez-Piqué E.1, Lin L.L.4, Moreno P.3, Wang M.S.5, Llanes L.1
2Xiamen Tungsten Co., China
3ALF-USAL, Spain
4Xiamen Golden Egret Special, China
5Xiamen Golden Egret, China
The use of fracture mechanics for rationalizing the fracture behavior of cemented carbides is validated, as far as sharp cracks, free of precracking-induced residual stresses and subjected to a well-defined stress state are used for assessing fracture toughness. However, machining a very sharp notch on the surface of hardmetals for fracture toughness testing has been a critical issue during many years. Within this framework, pulsed laser ablation techniques are here proposed, implemented and analyzed as innovative precracking routes within flexural testing procedures for reliable evaluation of fracture toughness on notched specimens. It includes machining of surface “through-thickness”, dimple-like and elongated micronotches. Research includes optimization of laser ablation parameters in terms of induced damage. Moreover, investigation addresses microstructural effects, by studying three WC-Co grades with different amount of metallic binder content, as well length scale issues linked to relative differences among micronotch and microstructural dimensions. For comparison purposes, fracture toughness testing is also conducted by means of flexural testing of single-edge precracked (long cracks) notch beams and Palmqvist indentation microfracture method.
HM 131
Evaluation of the Effect of Composition and Microstructure on the Coefficient of Friction and Galling Behavior of WC-Co Cemented Carbides
Sandoval D.A.1, Ther O.1, Cinca N.1, Mendez M.1
1Hyperion Materials and Technologies, Spain
Wear performance of WC-Co grades was investigated by means of reciprocating sliding versus a Ni alloy. The possible influence of amount of binder, WC size and amount of Cr3C2 were considered. Tests were conducted with WC-Co pins without lubrication to promote extreme conditions. Coefficient of friction was continuously recorded up to a sliding distance of 18 m. Average coefficients of friction of the last meters were used to compare the response of each WC-Co grade. Peaks and valleys found in plots were considered to evaluate the galling behavior. An analysis of variance showed that no significant correlation exists between the variables evaluated and their combination, and the properties of interest. However, experimental results and inspection by SEM showed that there are two critical combinations, both with the lowest Cr3C2 addition, for which the coefficient of friction increases: higher Co content and fine WC grain size; and lower Co content and medium WC grain size. An improvement on galling resistance could be expected for grades with higher Cr3C2 content and a fine WC grain size.
HM 132
Assessment of initial transfer of metal work material on cemented carbide tools -Influence of cemented carbide composition, microstructure and surface topography
Cinca N.1, Olson M.2
1Hyperion Materials and Technologies, Spain
2Dalarna University, Sweden
In many applications such as metal cutting and metal forming, cemented carbide tools work in sliding friction wear mode resulting in transfer of the metal work material. In these applications, a surface showing good anti-galling properties needs to be balanced with other desired carbide properties. In the present study, the metal transfer and friction characteristics of aluminum in sliding contact with cemented carbide were evaluated by performing tests under dry and lubricated conditions, where an Al tip is put into sliding contact with the cemented carbide under well-defined contact conditions. Cemented carbide grades include a straight WC-Co grade and two grades containing cubic carbides (i.e. TiC, TaC and NbC), to gain fundamental knowledge into the relation between microstructure and composition and anti-galling properties. Also, by varying the final polishing step of the cemented carbide, the influence of surface topography on the metal transfer and friction characteristics was evaluated. Post-test characterization using high resolution FEG-SEM and EDS has been used to show the influence of carbide composition (chemical affinity effects) and topography on the tendency to initial material transfer.
HM 133
Assessment of contact damage response of polycrystalline cubic boron nitride (PcBN) by means of spherical indentation
Gordon Pozuelo S.1, Rodriguez Suarez T.2, Roa Rovira J.J.1, Jiménez Piqué E.1, Franca L.F.P.2, Llanes Pitarch L.M.1
1Universitat Politècnica de Catalunya - EEBE, Spain
2Element Six (UK) Ltd, Global Innovation Centre, United Kingdom
The extremely severe conditions at which cutting tools are exposed in hard machining operations require tool materials with outstanding mechanical properties including, among others, thermal stability and chemical inertness. Excellent combinations of high hardness and fracture toughness are aimed to enhance wear and contact damage resistance and, thus, reliability of the tool itself. Here, spherical indentation is used to induce controlled damage, under monotonic loading up to values of 3000 N, and assess the mechanical integrity under service-like conditions of distinct polycrystalline cubic boron nitride (PcBN) grades. In doing so, PcBN grades with different cBN content, binder chemical nature and mean cBN grain size are investigated. Systematic and detailed inspection of residual imprints, by means of optical and scanning electron microscopy, is conducted to document critical loads for damage emergence and evolution through different stages as a function of microstructural assemblage. Attained results are rationalised on the basis of relative differences on hardness/fracture toughness correlation, which, in conclusion, translate into distinct cracking and fracture micromechanisms.
HM 134
Neutron diffraction characterizations of the thermal residual micro-stresses developed in NbC-Ni cemented carbides
Lavigne O.1, Luzin V.2, Labonne M.3, Lay S.3, Missiaen J.-M.3
1Hyperion Materials and Technologies, Spain
2ANSTO, Australia
3Université Grenoble Alpes, France
Cemented carbide composites develop very large micro-stresses due to the coefficient of thermal expansion (CTE) mismatch between the metallic carbide and the binder phases. This seriously affects abrasive and wear properties through microcracking and other physical behaviours under stress and load conditions. While micro-stresses developed in WC-Co systems have been investigated, there is not, so far, any information on the micro-stresses developed in NbC-Ni composites. This study aims to provide experimental data on this matter. The thermal micro-stresses developed in NbC-Ni systems were characterized by neutron diffraction. The results are presented in function of the Ni binder content (between 8 vol.% and 12 vol.%) and the sintered carbide grain size (between 2.5 µm and 12.8 µm). The NbC grain size was varied by controlling the holding time at high temperature during sintering and was measured subsequently by means of Electron Back Scattered Diffraction (EBSD) method. The Hashin-Shtrikman model gave reasonable interpretations in terms of the microstructure type of the composite (i.e., a NbC matrix with Ni inclusions).
HM 135
Uncover bonding mystery in immiscible metallic composites by spectroscopic microscopy
Zhao Z.1, Tang F.1, Hou C.1, Huang X.1, Song X.1
1Beijing University of Technology, China
Characterizing immiscible metallic composites with electron microscopy and X-ray spectroscopy is the classical way of obtaining their structural and physical details. Nevertheless, such a combination lacks ability to tell the interfacial interactions at grain boundaries. Here we demonstrate a novel strategy to uncover the bonding mystery in such systems by spectroscopic microscopy. The morphological and spectral data of samples was simultaneously recorded and analyzed, which revealed critical information regarding interfacial electronic modes. Taking W-Cu as a model, we experimentally quantified its connectivity and unambiguously identified conditional bonding between W and Cu. As a step further, we chemically reconstructed the specific W-Cu boundary that possessed the strongest interactions and investigated its atomic structure. The mechanism of W-Cu bonding was proposed and verified by first-principle calculations. The above methodology holds great promise to serve as a universal approach in achieving in-depth understanding of immiscible composites.
HM 142
Micro-mechanical testing and high-resolution characterization of cutting insert phases: Ti(C,N)/Zr(C,N) CVD hard coating, WC-Co substrate and TiN interface
El Azhari I.1
1Saarland University, Germany
Knowing the deformation behavior of wear resistant hard coating is essential for extending life time of cutting tools and pushing further their capabilities to withstand severe working conditions. Due to their micrometric length scale, investigation of intrinsic mechanical properties of these layers is challenging. Micro-mechanical testing (e.g. Micro-compression, microbeam bending, micro/nano-scratch testing…) emerges as new method to tackle this challenging task. In the present work, high resolution microscopy and micro-compression is deployed to investigate and compare deformation behavior of wear resistant CVD hard coating Ti(C,N) and Zr(C,N), WC-Co substrate and their respective hybrid combination at the interface.
17:00 - 20:00
Poster Session Refractory Metals - Additive Manufacturing
Location: Poster Hall I
Show all Abstracts
RM 47
Material Modelling and Finite Element Analysis in Metal Additive Manufacturing
Mashhood M.1, Baroli D.2, Wyart E.3, Zilian A.1, Peters B.1
1Université du Luxembourg, Luxembourg
2Euler Institute, Università della Svizzera italiana, Switzerland
3Réseau Lieu, Belgium
The additive manufacturing (AM) is competent method for the manufacturing of complex metal parts with wider process flexibility. During manufacturing, the metal part repetitively undergoes heating and cooling under the influence of laser passes and ambient conditions respectively. In turn, the material experiences the thermal strain and residual stress. The aim of the work is to predict them using certain material model. Where the solidified metal part from melt-pool is considered in current analysis. For numerical simulation, Finite Element Method (FEM) is chosen. The heat equation is first solved for thermal profile of AM Process. Afterwards, the structural analysis is performed with such thermal load. The non linear constitutive material model is utilized. For concerned material model, the temperature dependence upon the material properties is also implemented. The resulting  Finite Element Analysis (FEA) platform offers the macro-scale thermal solution and the prediction of resulting plastic distortion in material. This prediction however has become more accurate when the variable material property, depending upon the temperature of analysis zone, is introduced.
RM 48
Si3N4-based inks for Robocasting
Faria M.1, Olhero S.1, Oliveira F.1, Fernandes C.2, Figueiredo D.2
1University of Aveiro- Ceramic and Materials Engineering Dept., Portugal
2Palbit S.A, P.O Box 4, Portugal
Silicon nitride (Si3N4) based ceramics are well-established materials for several structural applications due to their combination of properties, such as mechanical strength, resistance to thermal shock, high hardness, and good wear resistance. Manufacturing Si3N4 ceramic parts with complex shapes by conventional subtractive techniques still is a great challenge that involves very high costs. Additive manufacturing (AM) appears as a promising alternative with large advantages for production of complex geometries, although there are few works in the literature for this particular material. Robocasting is an extrusion-based additive manufacturing method highly explored for ceramics,that uses high concentrated suspensions with low amounts of organic additives when compared with other AM technologies.    
In this work, aqueous-based Si3N4 inks containing yttria and alumina as sintering additives were developed for robocasting. Different amounts and types of dispersants were optimized by using rheological studies to attain suspensions with high-solid loading. The well-deagglomerated slurries were then turned into inks by fine-tuning the amounts of additives to achieve proper rheological behavior for the printing process. After printing and sintering structural and mechanical properties were evaluated.
RM 49
Advanced Heat-Resistant NiAl Based Alloys and Their Application in Technology of the Laser Powder Bed Fusion (LPBF)
Levashov E.1, Kaplanskii Y.1, Bashkirov E.1, Sanin V.1
1National University of Science and Technology "MISiS", Russia
The report presents overview of methods for producing narrow-fraction powder of NiAl-Cr-Co-(X) alloys which includes three chains: (1) centrifugal SHS casting, vacuum induction melting, plasma centrifugal atomization; (2) centrifugal SHS casting, grinding, plasma spheroidization; (3) elemental SHS, grinding, plasma spheroidization. The influence of alloying additives (X) on the high-temperature resistance to plastic deformation and oxidation has been investigated. It’s noted the evolution of structure and properties at stages: SHS, HIP, LPBF, LPBF+HIP+HT. Simultaneous precipitations of Laves Cr2Nb, Co2Nb, Heusler Ni2AlHf, (HfxNby)C phases provided a high level of properties. The improved alloy demonstrated the strength and creep resistance at T=900°C: σb=640 MPa, σ0.2=495 MPa; and at 25 °C: σb = 2720 MPa, σ0.2 = 1220 MPa, ε = 12%. This work was supported by the RF Ministry of Science and Higher Education within the framework of a state assignment 0718-2020-0034.
RM 51
Additive Manufacturing of Refractory Metals – Physical, thermal, mechanical and surface properties evaluation
Rebesan P.1, Candela S.1, Ballan M.1, Manzolaro M.1, Corradetti S.1, Gennari C.2, Pepato A.1, Vedani M.3
1National Institute for Nuclear Physics, Italy
2University of Padova, Italy
3Politecnico di Milano, Italy
Additive Manufacturing is among the best candidate technologies for the production of components with complex shapes. The Laser Powder Bed Fusion (LPBF) process gives the possibility to overcome obstacles that can be found with the traditional production processes and it allows to fabricate objects specially designed for assembly. However, the production of additively manufactured Ta, Mo, and W components faces some challenges due to their high melting point and affinity with oxygen at high temperature.
In this study, the process parameters are fine-tuned in order to manufacture high-density refractory metals parts by LPBF process. The samples are produced using a system with maximum laser power of 170 W. The material characterization is performed through the measurement of the physical properties, microstructural analysis, and the evaluation of mechanical and thermal performances. Surface roughness assessments and surface treatments are performed with appropriate parameters in order to improve the surface finish of AM components. The purpose of this extensive characterization is to verify the compatibility of physical, thermal, mechanical and surface properties of additively manufactured components with extreme technological applications.
RM 52
High temperature thermal and mechanical characterization of Mo samples produced with Laser Powder Bed Fusion
Ballan M.1, Rebesan P.2, Manzolaro M.1, Corradetti S.1, Campagnolo A.3, Pepato A.2, Meneghetti G.3
1INFN-LNL, Italy
2INFN-PD, Italy
3Università di Padova, Italy
Refractory metals as molybdenum can be employed for extreme technological applications, where high working temperatures are required, such as high efficiency ion sources for nuclear physics. Indeed they are designed to operate in high vacuum at temperatures around 2000°C, and are characterized by high geometrical complexity. The possibility to produce Mo components with Additive Manufacturing technologies such as Laser Powder Bed Fusion (LPBF) brings new opportunities in the field of ion source development. However, as the material properties are highly affected by the production method, an extensive characterization of the thermal and mechanical properties of Mo LPBF was performed and the obtained results were compared with data collected form standard Mo machined specimens.
Regarding the thermal characterization, it was possible to evaluate spectral emissivity and thermal conductivity in the temperature range of 600-1600°C making use of a custom set-up at INFN-LNL. For the mechanical measurements, tensile tests both at room temperature and at 600°C were carried out.
Although the AM samples were similar in density to standard Mo, the AM Mo properties resulted generally lower.
RM 53
Wire-Based Electron Beam Additive Manufacturing of Tungsten
Pixner F.1, Buzolin R.1, Warchomicka F.1, Pilz A.2, Enzinger N.1
1Graz University of Technology, Austria
2Plansee SE, Austria
In present study, the feasibility of wire-based additive manufacturing of commercially pure tungsten using electron beam technique could be demonstrated. Three different representative volumetric AM structures were built and subsequently characterized. The parts show a sound visual appearance with the absence of (macroscopic-) cracks or severe distortion. The fabricated parts exhibit high density and the value depends on the welding sequence applied; while the thin- and medium-walled structure has a relative density of ~100% and 99.875%, the measured relative density of the volumetric structure is slightly reduced to ~99.131% due to the smaller periodic bonding defect. However, a higher density could be achieved compared to powder-based processes on refractory metal. The mean hardness value of the fabricated AM structures is about 366 - 380 HV1 and is in the range of about 89 - 93% of the conventionally fabricated substrate of 410 ± 39 HV1. Microstructural changes for all AM structures could be observed; a coarsening of the grains from the bottom to the top and a change in morphology can be noted for all AM structures. While the coarsening is quite severe for the thin-walled structure, it is moderate for the volumetric AM structure due to the change in thermal boundary conditions. During deposition, the microstructure in the substrate also changes and exhibits a coarse-grained heat-affected zone, although the grain size is still comparatively smaller than in the AM bulk material.
RM 61
Laser-based additive manufacturing of Mo-Si-B alloys new
Krüger M.1, Schmelzer J.2, Fichtner D.2, Heinze C.2, Rittinghaus S.-K.2, Weisheit A.2
1Otto-von-Guericke Universität Magdeburg, Germany
2Otto-von-Guericke-Universität Magdeburg, Germany
Materials for structural applications at ambient and high temperatures are faced with enormous requirements concerning static and cyclic mechanical loadings, damage tolerance and oxidation resistance. In the last decades refractory metals and their alloys were more and more considered as potential alloys for these requirements.
Besides others, Mo-rich Mo-Si-B alloys are in the focus of research on innovative turbine materials, as they provide high strength at ambient temperatures and sufficient fracture toughness as well as high thermal resistance and excellent creep strength. Simulations, structural analyses and comparative experimental assessments against Ni-base superalloys already demonstrated the outstanding performance of Mo-Si-B alloys. In terms of bulk processing two general approaches were followed in the past, i.e. processes that are based on phase transformations from a molten phase (classical ingot metallurgy, directional solidification) or processes based on diffusion and/or phase transformation mechanisms in the solid state (powder metallurgical processes). The classical melting processes are very energy-consuming and costly due to ultra-high melting points of Mo-based materials up to 2600°C, and does not allow a high degree of freedom in terms of tailoring properties due to inhomogeneous microstructural evolution of the individual phases. An exception are eutectic or near-eutectic alloys having a melting point < 2100 °C, which show very fine network-like microstructures. Such eutectic microstructures can be grown directionally to provide anisotropic materials properties. The more established processes are powder metallurgical (PM) processes that avoid phase evolution from the melt and therefore, allows the formation of very fine-grained and homogenous microstructures with typical isotropic properties. Furthermore, by PM techniques different additional elements or compounds can be incorporated in the alloys to modify their properties in a wide range. However, using the above-mentioned processing methods extensive mechanical finishing will be necessary to produce complex parts like turbine blades with cooling structures. This is challenging due to the extremely hard silicide phases in Mo-Si-B alloys.
In our present approach we use the basic knowledge on the microstructural evolution and phase compositions of Mo-Si-B alloys and we assess the potential of generative and additive manufacturing methods aiming in processing of net-shaped material. Therefore, the laser-based processes direct energy deposition (DED) as well as laser powder bed fusion (L-PBF) were used to build multi-phase Mo-Si-B alloys from spherical gas atomized (GA) powders. After GA the powders were sized into fractions of +45/−90 μm for the DED and +15/–45 μm for the LPBF process. As it is known from refractory powders that they absorb impurities from the environment over time, especially embrittling oxygen, the powders were heat treated before processing to “clean” the surfaces and therefore, avoid crack formation in the AM builds. For successful processing of crack-free Mo-Si-B samples high pre-heating temperatures are used, i.e. approx. 700 °C for the DED process and up to 1200 °C for the LPBF process. The microstructures of the AM builds were investigated in terms of their microstructural evolution by SEM and EBSD methods. Phase fractions of the as-built Mo-rich Mo-Si-B alloys were determined and compared to literature data of existing phase diagrams and other Mo-Si-B alloys. The ambient and high temperature mechanical properties were determined by means of hardness measurements, three-point bend tests and compressive creep tests.
17:00 - 20:00
Poster Session Refractory Metals - High entropy alloys and RM intermetallics
Location: Poster Hall I
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RM 54
Model supported determination of the process window for aluminothermic synthesis of refractory high entropy alloys
Maier C.1, Friedrich B.1
1IME Institute for Process Metallurgy and Metal Recycling, RWTH Aachen University, Germany
Today’s potential production methods for high entropy alloys show difficulties as they involve high-purity metals and reveal high energy consumption. In contrast, metallothermic reduction generally allow for improving cost  and time factors and thus overall efficiency by the use of exothermic enthalpy released. Such, after successful proof-of-principle tests for equimolar high entropy alloys, this paper investigates the generation of binary to quinary alloys consisting of the elements Al, Cr, Mo, Ti and V as boundary systems.

To understand the complex reaction mechanisms of aluminothermic reduction of multicomponent alloys, thermochemical modelling is carried out using FactSage 8.0. Based on the outcome, the experimental parameters are derived allowing to reach the targeted alloy composition while simultaneously optimizing the input material mixture. Experimental validation takes place in 10 kg scale. Metal samples are analyzed via atomic emission spectroscopy, slag samples via X-ray fluorescence spectroscopy. Furthermore, X-ray diffraction analysis is carried out to investigate the obtained products on phase composition. As the fundamental work proves the concept the paper will also present results of the final alloy synthesis work.
RM 55
Refractory High Entropy Alloys for structural material of High Temperture Gaz Cooled Reactor
Dhers J.1
1Framatome, France
High temperature gas cooled reactors are submitted to a harsh environment: high temperature, corrosion due to the pollution of the gas and irradiation.
Some material solutions already exist but they show some limitations. In order to overcome those limits, we must look at new innovative solution that can ideally answer to all the requirements. Refractory HEA may be in the future a solution. Here are presented some alloys that have been already investigated, but not specifically nuclear oriented. It and can be the start of a more important work on material solution for those types of advanced reactors.
RM 56
Investigation of MoNbTaW-X (X=Ti,V,Cr,Mn,Hf) refractory high entropy alloy thin films deposited by high power impulse magnetron sputtering
Gruber G.C.1, Lassnig A.2, Zak S.2, Gammer C.2, Cordill M.J.2, Franz R.1
1Montanuniversität Leoben, Austria
2Austrian Academy of Sciences, Austria
Refractory high entropy alloys (HEAs) represent a new class of materials that show promising properties, such as high hardness, good thermal stability and sluggish diffusion, which makes them suitable for various potential applications. Within this study a series of refractory HEAs was deposited using high power impulse magnetron sputtering keeping the base alloy MoNbTaW constant and adding a fifth element: Ti, V, Cr, Mn or Hf. The targets used for the synthesis of each alloy contained all five elements in an equimolar concentration. As analyzed by X-ray diffraction and transmission electron microscopy, all films showed a bcc solid solution phase structure in as-deposited state. Further, the thermal stability of the Cr containing HEA films was analyzed by annealing the sample in a vacuum furnace. The performed work is intended to contribute to a comprehensive understanding about the phase and thermal stability of refractory HEA thin films.
17:00 - 20:00
Poster Session Refractory Metals - Surface engineering and coating
Location: Poster Hall I
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RM 60
Galvanic Corrosion of Molybdenum Alloys and Oxides in contact with Copper for Thin Film Transistors using Evans Diagrams
Riedl J.1, Mori G.1, Schmidt H.2, Köstenbauer H.3
1Montanuniversität Leoben, Austria
2Plansee, China
3Plansee, Austria
Molybdenum (Mo) is commonly used as reliable and well conducting material for metallization in various thin film transistor (TFT) applications. In advanced displays with additional functional layers, like highly absorbing Mo oxide layers to reduce the amount of reflected ambient light, the impact of  galvanic  corrosion is increased as the combinations of used material are getting more complex. It has been observed that TFT panel producers notice substantial material loss after the etching process during photoresist removal (stripping), due to galvanic corrosion. Therefor three different Molybdenum materials have been investigated. Galvanic corrosion behavior was investigated by measuring Evans diagrams in contact with Copper. Results have shown that it is of crucial importance that a Mo material contains a passivating element such as Titanium or Tantalum in a proper concentration to form a stable passive layer to avoid attack caused by the electrolyte. Also water content of the electrolyte plays an important role for material behavior.
20:00 - 20:00
End of sessions
Location: Poster Hall I