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Technical Program

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Status: 18 April, 2025
Thursday, 5 June, 2025

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08:30 PRO04-C 1
Ultrafine-grained tungsten via pressureless two-step sintering
Li X.1, Zhang L.2, Qu X.2
1University Of Science and Technology Beijing, China
2University of Science and Technology Beijing, China
Abstract
Refining the as-sintered microstructure to ultrafine-grained and ultimately to nanocrystalline grain size and with low porosity and high spatial uniformity is much desired in terms of improved properties and reliability. In this work, the challenge of producing dense ultrafine-grained tungsten is hereby addressed by a simple pressureless two-step sintering method. It provides a uniform microstructure with ~99% theoretical density and submicron grain size. Benefitting from the finer and more uniform microstructures, two-step sintered samples show better mechanical properties in terms of bending strength and hardness. While parabolic grain growth kinetics is verified, a transition in nominal grain boundary mobility was observed at 1400 Celsius degree, below which grain boundary motion is rapidly frozen with unusually large activation enthalpy of ~12.9 electron volt. A phenomenological explanation is provided for this, which underlies the two-step sintering method. We believe the as-reported method and mechanism should also be applicable to other refractory metals and their alloys.
08:50 PRO04-C 2
Liquid Phase Sintering of Molybdenum Alloys with Ni-Cu Binder
Ranot H.1, Upadhyaya A.1
1IIT Kanpur, India
Abstract
This study investigates the effects of Ni-Cu binder composition on the densification, microstructural evolution, phase evolution, shape retention, and mechanical behaviour of Mo alloys processed via liquid phase sintering. The objective is to identify an optimal binder composition for the cost-efficient production of dense, near-net-shape Mo alloys with superior mechanical performance. Results show that increasing the Ni-Cu ratio enhances the sinter ability of Mo compacts, though excessive Ni leads to geometric distortion. Ni-rich binders create two liquid phases during sintering, each with varying Mo solubility, resulting in a dual-phase matrix upon solidification. Stereological quantification reveals that Mo alloys exhibiting low matrix volume fractions, high Mo grain contiguity, and large dihedral angles demonstrate strong structural integrity and resistance to geometric distortion. In contrast, those with high matrix volume fractions, low grain contiguity, and elevated Mo solubility in the binder show improved strength, hardness, and ductility. This study underscores the potential of tailored Ni-Cu binder compositions to optimize the liquid phase sintering process for high-performance Mo alloys, paving the way for low-cost, large-scale production.
09:10 PRO04-C 3
The influence of the Nitrogen Hydrogen gas ratio on properties of industrial Tungsten Heavy Alloys
Cury R.1, Granzer T.2, Mahot P.1, Dartus L.1, Schneider J.2, Stahl R.3, Glotfelty C.3
1Plansee Tungsten Alloys, France
2Plansee Composite Materials, Germany
3Mi-Tech Tungsten Metals, LLC, USA
Abstract
Tungsten heavy alloys are composite metallic alloy manufactured using pure tungsten and other elemental materials mixed at powder state. Pressed parts are liquid sintered under reductive atmosphere. Hydrogen is frequently used as reduction gas, reacting specifically with oxygen, carbon and sulfur, promoting with the sintering process the assessment of metallic bond. For some years, the consumption of hydrogen in the industry is under scrutiny: although it is seen as a sustainable gas in metallurgy (notably compared with carbon monoxide) , most of the hydrogen production is coming from non-sustainable sources like oil. It is essential to investigate the possibility of sintering tungsten heavy alloys with a mixture of hydrogen and nitrogen. The effect of the gas mixture is therefore investigated on mechanical and morphological properties, compared with the standard industrial product.
09:30 PRO04-C 5
Liquid metal embrittlement in the brazing of refractory metals
Wagner J.1, Mayr-Schmölzer B.1, Ploner K.1, Rüttinger M.1, Lorich A.1
1Plansee SE, Austria
Abstract
Liquid metal embrittlement (LME) may occur during brazing when materials are under stress and simultaneously exposed to molten brazing filler metal. The sensitivity of refractory metals and alloys for LME in contact with an active braze alloy consisting of copper, silver and titanium has been studied. Molybdenum, TZM, tungsten, TaW2.5 and TaW10-alloys were investigated in a high-temperature three-point bending test at 950°C at different stress values. It is shown that the ductility of all tested materials reduced significantly in contact with the liquid active braze alloy. The failure mechanism was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX) to be predominantly intergranular cracking. The findings shown in this work highlight the importance of controlling stresses during brazing processes.
09:50 PRO04-C 6
In-vivo evaluation of molybdenum as bioabsorbable stent candidate
Sikora-Jasinska M.1, Morath L.1, Kwesiga M.1, Plank M.1, Nelson A.1, Oliver A.2, Bocks M.3, Guillory R.1, Goldman J.1
1Michigan Technological University, USA
2Mayo Clinic Graduate School, USA
3Case Western Reserve School of Medicine, USA
Abstract
Biodegradable stents have tremendous theoretical potential as an alternative to bare metal stents and drug eluting stents for the treatment of obstructive coronary artery disease. Any bioresorbable or biodegradable scaffold material needs to possess optimal mechanical properties and uniform degradation behavior that avoids local and systemic toxicity. Recently, molybdenum (Mo) has been investigated as a potential novel biodegradable material for this purpose. With its proven moderate degradation rate and excellent mechanical properties, Mo may represent an ideal source material for clinical cardiac and vascular applications. The present study was performed to evaluate the mechanical performance of metallic Mo in vitro and the biodegradation properties in vivo. The results demonstrated favorable mechanical behavior and a uniform degradation profile as desired for a new generation ultra-thin degradable endovascular stent material. Moreover, Mo implants in mouse arteries avoided the typical cellular response that contributes to restenosis. Together, the results suggest that the products of Mo corrosion may exert beneficial or inert effects on the activities of inflammatory and arterial cells.

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08:30 SE13-C 1
On the phase formation and properties of refractory-metal based high-entropy silicide coatings
Kirnbauer A.1, Peck E.1, Kolozsvari S.2, Polcik P.2, Mayrhofer P.H.1
1TU Wien, Thin Film Materials Science Division, Austria
2Plansee Composite Materials GmbH, Germany
Abstract
Silicides are known for their exceptional high-temperature properties and especially their oxidation resistance. In this study we want to combine the high-entropy concept, which has proven to enhance high-temperature properties of nitrides and borides, with the already good oxidation resistance and thermal stability of binary silicides. Therefore, we investigate the structure, mechanical properties, and thermal stability (in vacuum and ambient air) of refractory-metal based high-entropy silicides. The investigated coatings are synthesized by magnetron sputtering and show a single-phased hexagonal structure. The hardness and indentation modulus are with 17.3 ± 0.3 GP and 322 ± 5 GPa in the range of binary transition metal (TM) silicides. Upon oxidation several complex TM-oxides are formed leading to significantly decreased mechanical properties. Vacuum annealing of coated sapphire substrates up to 1200 °C leads to an increase of the hardness to ~19 GPa which might be attributed to a slight age-hardening effect as different silicide phases are detected by XRD. Annealing up to 1400 °C leads to recovery and recrystallisation and causes a drop the hardness to ~12 GPa.
08:50 SE13-C 2
Tuning properties of diborides by transition metal alloying deposited by combination of magnetron sputtering and cathodic ARC evaporation
Karpinski D.1, Lümkemann A.1, Krieg C.1, Karvankova P.1, Heiko F.2, Joost H.2, Soucek P.3, Vasina P.3, Klimashin F.4
1Platit AG, Switzerland
2GFE Schmalkalden, Germany
3Institute of Physics and Plasma Technology, Masaryk University, Czech Republic
4Swiss Federal Laboratories for Materials Science and Technology, Switzerland
Abstract
Titanium diboride is currently the most widespread metal boride (MeBx) coating used in industry due to its outstanding properties such as high hardness >40 GPa, high melting point >3000 °C, and low propensity for sticking to soft metals. The main drawbacks of diborides are their generally low oxidation resistance (<800°C for TiB2) and brittleness. This study investigates the effect of alloying MeBx with transition metals on the structure, mechanical and tribological properties, and oxidation resistance of the coating. The coating deposition was performed in a Platit Pi411 machine with LACS® technology which includes simultaneous magnetron sputtering from a central cylindrical cathode (SCiL®) and a cathodic arc evaporation from cylindrical cathode located in the chamber door (LARC®). Here, the MeBx target was sputtered, and cathodic arc evaporation of Ti or Cr target was used for alloying the coating. XRD, HRTEM structure study, nanoindentation and isothermal annealing in air at Ta=600–900°C revealed that by alloying of MeBx we can form the nanolaminate microstructure, tune the hardness and modulus, and enhance oxidation resistance of the coating, respectively.
09:10 SE13-C 3
Superstoichiometric (Al,Cr)Nx Coatings with Superior Hardness, Fracture Toughness, and Wear Resistance
Klimashin F.F.1, Učík M.2, Matas M.3, Holec D.3, Beutner M.4, Klusoň J.2, Jílek M.2, Lümkemann A.5, Michler J.1, Edwards T.E.J.1
1Empa – Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Switzerland
2PLATIT a.s., Czech Republic
3Montanuniversität Leoben, Chair of Physical Metallurgy, Austria
4Otto von Guericke University, Chair of Manufacturing Technology with Focus Machining, Germany
5PLATIT AG, Switzerland
Abstract
Many transition-metal carbides, nitrides, and oxides are inherently non-stoichiometric compounds, characterised by broad homogeneity ranges in their phase diagrams. Deviations from stoichiometry, defined as the ratio of non-metal to metal atoms (x), can drastically affect properties. While substoichiometric compounds (x<1) have been widely studied, superstoichiometric compounds (x>1) remain largely unexplored.
In this study, we synthesised a series of superstoichiometric (Al,Cr)Nx coatings via reactive sputtering at power densities up to 840 W/cm². Experimental and computational analyses reveal that excess nitrogen primarily occupies interstitial lattice sites. Upon surpassing a critical concentration (x≈1.06), grain renucleation rates increase, disrupting columnar growth and altering the preferential orientation from (111) to (220). The coatings exhibit a single-phase, face-centred cubic structure, a dense microstructure, and reduced surface roughness compared to benchmark coatings produced by cathodic arc evaporation.
Remarkably, hardness, fracture toughness, and wear resistance equal or exceed those of the benchmark coatings. Our findings highlight the advantages of superstoichiometric (Al,Cr)Nx as effective wear-resistant materials for advanced engineering applications, while also suggesting broader implications for the utilisation of superstoichiometric nitrides across various industries.
09:30 SE13-C 4
Magnetron Sputtering of Advanced Multi-elemental Aluminide Thin Films: Impact of alloying with refractory metals cancelled
Ott V.1, Dürrschnabel M.1, Kolozsvari S.2, Polcik P.2, Wojcik T.3, Riedl H.3, Mayrhofer P.3, Stüber M.1
1Karlsruhe Institute of Technology, Germany
2Plansee Composite Materials GmbH, Germany
3TU Wien, Austria
Abstract
Intermetallic phases in the CsCl structure have promising properties for use in highly demanding environments. Major limitation for potential applications is the brittle failure at room temperature. The RuAl phase in B2 structure is an outstanding candidate of this material class due to its ductile behavior at room temperature. To further improve this material, alloying with refractory metals can help to increase the maximum service temperature, improve ductility and at the same time maintain good oxidation resistance.
To achieve this goal, thermally activated phase formation in nanoscale multilayer precursors is used to obtain single phase multi elemental aluminides with tailored properties. The partial substitution of Ru with the stable oxide forming alloying element Cr or with the Ru affine element Hf, while maintaining the Al content at 50 at% is aiming at improving the oxidation resistance and mechanical properties. In-situ HT-XRD is used to observe the phase formation during the heat treatment of single phase (Ru, RM)Al (RM=Cr, Hf) and the resulting microstructure, characterized by TEM, is linked to their mechanical and oxidative properties.
09:50 SE13-C 5
HiPIMS deposition of hard coatings in the Ti-Al-N system with tailored mechanical properties
De Souza Lamim T.1, Martinez-Martinez D.1, Chemin J.-B.1, Fleming Y.1, Philippe A.-M.1, Valle N.1, Penoy M.2, Useldinger R.2, Bourgeois L.2, Choquet P.1
1Luxembourg Institute of Science and Technology, Luxembourg
2Ceratizit Luxembourg, Luxembourg
Abstract
Nitrides of transition metals are typically used for protective applications in harsh situations (e.g. coating tools) where a combination of different characteristics is mandatory, e.g. good mechanical properties, high oxidation and wear resistance. This work explores the deposition of Ti-Al-(Si)-N single and multilayers to engineer their microstructure and mechanical properties.
Depositions using targets with an Al/Ti ratio of 1 lead to the formation of hard (~35 GPa) single layers composed of a well-formed cubic nitride phase, although the presence of Si alters the texture. In contrast, a softer (~25 GPa) poorly formed hexagonal nitride is observed if the Al/Ti ratio increases to 1.5.
Multilayers (1:1) composed of cubic phases show a columnar growth comparable to single layers, although chemical alternation is detected. In contrast, a dense microstructure is observed in equivalent multilayers composed of cubic and hexagonal phases, indicating that the difference between both phases is enough to interrupt the columnar growth. The hardness of these 1:1 multilayers is that of its softer constituent. An optimal multilayer combining dense microstructure and excellent hardness is presented.

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10:30 SE13-D 1
Microstructural, Alloying, and Architectural Effects on the Fracture Toughness of hard CrN Coatings
Hahn R.1, Rosenecker S.1, Forstner D.1, Wojcik T.1, Boebel K.2, Jerg C.2, Kolozsvári S.3, Polcik P.3, Mayrhofer P.H.4, Riedl H.1
1CDL-SEC, TU Wien, Austria
2Oerlikon Balzers, Oerlikon Surface Solutions AG, Liechtenstein
3Plansee Composite Materials GmbH, Germany
4Institute of Materials Science and Technology, TU Wien, Austria
Abstract
Physical vapor-deposited CrN is a well-established protective coating material used in diverse tribological applications due to its hardness and Young's modulus. As a potential candidate for replacing CrVI-containing deposition routes, the fracture toughness (KIC) of this transition metal nitride is highly interesting, whereas a more ductile character would be required in many applications. This study examines the influence of microstructure on fracture properties in cathodic arc-evaporated CrN coatings using in-situ micromechanical cantilever bending tests. By varying the deposition parameters and architectures, we demonstrated that the influence of column size on toughness could be excluded. Conversely, the constitution of the column boundary, determines the fracture toughness. The selective alloying of silicon increased hardness (27.5 GPa) and toughness (2.7 MPa·m0.5), although a reduction in Young's modulus accompanied this. The highest KIC (3.7 MPa·m0.5) was achieved using a superlattice architecture of CrN and TiN layers, representing an 85% improvement in toughness, attributed to coherent stress fields due to different lattice parameters. The present study offers an overview of strategies for enhancing KIC without compromising other mechanical properties.
10:50 SE13-D 2
Fabrication and properties of hard coatings by a hybrid PVD method
Wang Q.1, Xu Y.1, Wu Z.1
1Guangdong University of Technology, China
Abstract
To increase the lifetime and performance of cutting tools, there are increasing demands for high -performance coatings. Coatings for cutting tools require combinations of properties such as a relatively high hardness, good adhesion, wear and oxidation resistance. To fulfill these requirements, new coating materials and new synthesizing methods are needed to be developed. By combining vacuum arc and magnetron sputtering or high power impulse magnetron sputtering, the hard coatings with various multicomponent compositions and attractive mechanical properties, modulated residual stresses, and improved high-temperature properties can be fabricated. Among them, some of the coatings were tailored to obtain excellent cutting performance on the high-speed cutting tools. In this presentation, some nitride and oxide hard coatings, such as AlTiN/AlCrN, AlTiN/TiSiN, AlCrO, etc. were deposited by a hybrid PVD coating system. The related coating microstructure, mechanical properties, and cutting performance will be presented.
11:10 SE13-D 3
Stabilised oxygen-containing PVD coatings for high application temperatures
Joost H.1, Frank H.1, Schiffler M.1
1GFE - Gesellschaft für Fertigungstechnik und Entwicklung Schmalkalden e.V., Germany
Abstract
High thermal and mechanical loads occur when machining difficult-to-cut materials and in high-performance machining. Low thermal conductivity and ductility of these materials render machining with geometrically defined cutting edges challenging, resulting in oxidative, abrasive and adhesive wear. Oxygen-containing, AlCrN-based coatings provide enhanced protection  against oxidation. As part of a research project, the optimization of such coatings was achieved by varying the oxygen content (0-5%), the use of additional alloying elements (e.g. Zr, Si, Ti, B) and adapted process conditions, with the objective of improving the tribological properties at high operating temperatures. The thermal and tribological behaviour of the coatings was investigated through the utilization of an oscillating friction wear test at 900°C, on a newly designed temperature measuring station, in addition to practical tests such as the longitudinal turning of 1.4305. A infrared camera was employed to facilitate a comprehensive analysis of the thermal loads. The findings revealed the intricate impact of material selection, coating parameters and structures on stability and performance. All coatings were manufactured on an industrial coating system (pi411, Platit).
11:30 SE13-D 4
Temperature stability of high entropy ceramic coatings from Cr-Hf-Mo-Ta-W refractory metal system
Souček P.1, Debnárová S.1, Fekete M.1, Zuzjaková Š.2, Lin S.3, Jašek O.1, Pitoňáková T.1, Koutná N.3, Zeman P.2
1Masaryk University, Czech Republic
2University of West Bohemia, Czech Republic
3Technische Universität Wien, Austria
Abstract
High entropy alloys are multicomponent materials containing at least five principal elements with contents ranging between 5 and 35 at.%. The high entropy concept also extends to ceramics, such as oxides, nitrides, borides and carbides.
In this contribution, we are examining the temperature stability of high entropy nitrides from the Cr-Hf-Mo-Ta-W system. Magnetron sputtering was used for the depositions on Si and alumina substrates. An ambient temperature was used for the first deposition set, while an elevated temperature of 700°C was used for the second. All the deposited coatings exhibited strong diffraction peaks corresponding to an fcc lattice expected for the formation of these high entropy ceramics. The coatings were annealed to 1000°C and 1200°C to observe the changes in their chemical composition, phase and crystal structure, morphology and mechanical properties. We will discuss the coating’s adhesion playing a significant role in the to withstand annealing, the influence nitrogen loss on changes in the coating’s structure and properties and identifying critical elements for enhancing the temperature stability.

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10:50 RE98-A 1
Comprehensive Review of Rhenium Production and its Environmental Impact - KEYNOTE
Segura J.1, Soto C.1, Edgardo C.1
1Molibdenos y Metales S.A., Chile
Abstract
Rhenium, essential for aeronautical turbines, oil refinery catalysts, and potentially new uses like medical implants and green hydrogen production, is primarily extracted from molybdenite, a byproduct of copper mining. The extraction process includes molybdenite concentration, roasting and gas treatment to capture rhenium. In Molymet’s case, pretreatment is done at facilities in Belgium, Chile, and Mexico, and final processing in Chile. A cradle-to-gate life cycle assessment (LCA) was conducted following ISO 14044 to evaluate the environmental impacts of this process. Key impact categories such as global warming potential, water consumption, and human toxicity were assessed using the 2022 dataset and secondary LCA databases. The study found that the molybdenum concentrate and pretreatment plants contribute the most to environmental impacts, with rhenium’s global warming potential (GWP) at 511 kg CO₂ eq/kg—considerably lower than other specialty metals like palladium and ruthenium. These findings offer valuable insights to support Molymet’s sustainability strategy.
11:20 RE98-A 2
Production of spherical rhenium powder and its optimization for Powder Bed Fusion technology.
Ponce A.1, Segura J.1, Cisternas E.1
1MOLYMET, Chile
Abstract
Rhenium and its alloys have attracted renewed interest in the aerospace sector for their heat-resistant properties. But, particularly in the case of pure rhenium, the production of complex parts is very difficult due to the extreme work-hardening effects of this material and therefore the new additive manufacturing (AM) techniques have been gaining momentum. High purity, uniform particle size and high flowability are key properties of powders for AM. Molymet has recently installed and commissioned a plasma atomization system to produce spherical powders for the manufacturing of rhenium-based parts. After careful development of the raw material feedstock and process parameters, high yields of spherical metallic rhenium were achieved, with particle sizes ranging from 15 to 45 microns, flowability <10 sec/50 g and oxygen content under 500 ppm—ideal properties for AM applications. The suitability of this material for additive manufacturing was tested using powder bed fusion with laser beam/metal (PBF-LB/M) technology. A study was conducted to determine the optimal manufacturing parameters, including laser power, scanning speed, and hatch distance, aiming to achieve 98% relative density, minimize internal defects, and reduce surface roughness in cubic samples.
11:40 RE98-A 3
Structure and mechanical properties of laser powder bed-fused and HIP-ed Mo and Mo8Re components: a comparative study
Leclercq A.1, Mouret T.1, Brailovski V.1
1Ecole de Technologie Supérieure de Montréal, Canada
Abstract
Molybdenum belongs to the refractory metals group and is one of the target materials for laser powder bed fusion 3D printing. This study aims at improving the printability of molybdenum by alloying it with rhenium and enhancing its mechanical properties using hot isostatic pressing (HIP) as a post-treatment. To this end, a custom-made Mo8Re (wt.%) plasma spheroidized powder was used to print specimens, which were then HIP-ed (1800°C, 150 MPa, 3 h) and characterized in terms of their density, structure and compression behavior in the 20-1000oC temperature range. For the as-printed specimens, rhenium addition increased the printing density from 97 to 98% without modifying the mechanical properties in the studied temperature range. After the HIP treatment, the Mo8Re specimens reached a maximum compression stress of 900 MPa at 20oC (140 MPa at 1000°C) and a maximum compression strain of 30% at 20°C (8% at 1000°C), which represent an almost twofold increase in strength and around 70% increase in strain as compared to pure molybdenum specimens with the same HIP conditions.

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13:00 CAT15-A 1
Quantification of Plastic Deformation in Hardmetal Tool Inserts at the Macroscopic and Microstructural Level - KEYNOTE
Tong V.1, Jones C.1, Roebuck B.1, Walsh M.2, Alm P.3, Olovsjö S.3, M'Saoubi R.3, Gee M.1, Mingard K.1
1NPL, United Kingdom
2Seco, United Kingdom
3Seco, Sweden
Abstract
The need to minimise wear of hardmetal cutting inserts requires an understanding of, and in turn accurate measurement of, both the external changes in dimensions and the internal microstructural changes which cause plastic deformation underneath the tool coating.
This paper summarises development of methods to quantify the dimensional changes of the complex 3D tip shape of a tool and, from the same tool, quantify the plastic deformation characteristics of the underlying microstructure that determine the external 3D change of shape.
Dimensional changes of the tip shape have been measured using a 3D optical microscope to quantify the small, micrometre scale changes of the worn tip relative to the no-longer-present original surface.  The tips have then been sectioned on a well-defined plane relative to the cutting force and the microstructure mapped over large areas at high resolution.  Methods to quantify the defects produced by the high temperature creep processes have been evaluated and compared with the external shape change and fundamental creep properties of the hardmetal grades used.
13:30 CAT15-A 2
Hot Deformation Behaviour of Cemented Carbides: Constitutive Analysis and Microstructural Insights
Collado Ciprés V.1, García J.2, Cabrera J.M.3, Llanes L.3
1AB Sandvik Coromant R&D + Universitat Politècnica de Catalunya (UPC), Sweden
2AB Sandvik Coromant R&D, Sweden
3Universitat Politècnica de Catalunya, Spain
Abstract
The hot deformation behaviour of WC-Co cemented carbides was investigated during compression at temperatures from 700 to 1000 °C and strain rates from 0.0005 to 0.1 s-1. Constitutive equations were used to develop a physically based model describing the stress as a function of strain rate, temperature and microstructural parameters. An initial study focusing on Co revealed the occurrence of dynamic recrystallization (DRX), with dislocation glide and climb being the dominant deformation mechanism. The activation energy matched that of Co self-diffusion, confirming that deformation in Co was diffusion controlled. Increased resistance at 700 °C was attributed to limited dislocation climb. The mechanical resistance of WC-Co was described by three stress terms: those carried by the binder phase, those accommodated by the carbide phase and those associated with the interaction between the phases. EBSD analysis emphasized the importance of the WC skeleton and the microstructural arrangement. Both Co and WC presented plastic deformation, with cobalt providing ductility and WC accommodating most of the stress.
13:50 CAT15-A 3
Temperature and strain rate dependence of flow stress of WC-Co cemented carbides under high temperature compressive deformation
Komamura Y.1, Ichikawa R.1, Koseki S.1
1Mitsubishi Materials, Japan
Abstract
In order to understand the high-temperature deformation mechanisms of WC-Co cemented carbides, the strain-rate sensitivity m and the apparent activation volume v were measured for WC-10mass%Co and WC-15mass%Co cemented carbides, respectively, at strain rates between 10^-5 s^-1 and 10^-3 s^-1 and temperatures between 973 K and 1273 K with different grain sizes of WC. The coarse-grained cemented carbides exhibited m values of 0.04-0.10, and v increases monotonically with decreasing stress, showing 2-6 b^3 where b is the magnitude of the Burgers vector of WC. The submicron-grained cemented carbides exhibited similar deformation behavior to the coarse-grained cemented carbides in the high stress region, but in the low stress region, m exceeded 0.10 and v decreased to 3 b^3. It was concluded that plastic deformation is dominated by dislocation glide of the WC phase in the high stress region of submicron-grained cemented carbides and in the full stress region of coarse-grained counterparts, while in the low stress region of submicron-grained cemented carbides, plastic deformation is dominated by dislocation creep of the WC phase.
14:10 CAT15-A 4
Study on the compressive behavior of ultra-coarse WC-8 wt.% Co cemented carbide
Zhang X.1, Xie H.1, Liu Y.1, Qiu W.1
1Xiamen Golden Egret Special Alloy, China
Abstract
This paper investigates the compressive behavior of ultra-coarse WC-8wt.%Co cemented carbide, which is ideal for harsh conditions such as high temperature, high pressure and high impact, using mechanical property analysis, EBSD and TEM. The study reveals that the compressive deformation of ultra-coarse cemented carbide occurs in three stages: elastic, plastic, and fracture. During the elastic deformation stage, the binder phase undergoes martensitic transformation from FCC to HCP, and the WC grains experience dislocation and slip activity. This leads to a 60% HCP phase in the binder, causing a slight decrease in hardness and a notable increase in coercive force due to residual stress. In the plastic deformation stage, further HCP transformation is limited, resulting in slip along WC/WC grain boundaries and the formation of micro-cracks. This causes a gradual decrease in hardness and a 65% increase in coercive force compared to the initial state. The fracture deformation stage involves increased slip at WC/Co interfaces, leading to additional micro-cracks, a significant 6% decrease in hardness, and a 140% increase in coercive force before the ultimately fails.

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13:10 SIM07-A 1
Systematic Investigation of Phase Stability in Refractory High Entropy Alloys Using First Principles
Lechner K.1, Wagatha P.2, Knabl W.2, Helmut C.1, Holec D.1
1Montanuniversität Leoben, Austria
2Plansee SE, Austria
Abstract
Refractory High Entropy Alloys (RHEAs) offer exceptional mechanical and thermal
properties such as high-temperature strength and might exhibit high-temperature oxi-
dation and corrosion resistance. We focus on exploring Mo-Nb-Ta-W-X alloy systems
primarily for their thermal stability. Although the four elements are fixed, searching
the compositional space remains a significant challenge. In this work, we present a
theoretical workflow for systematic investigations of the phase stability of RHEAs. The
source data come from two sources. On one hand, Density Functional Theory (DFT)
calculations are performed. On the other hand, data from trusted DFT repositories are
employed as much as possible to minimize computational efforts. The results will be
used to identify promising candidates for further validation both computationally and
experimentally.
13:30 SIM07-A 2
Advanced Characterization and High Performance Computing Modeling of Tungsten Grain Growth during Hydrogen Reduction
Estupinan Donoso A.1, Besseron X.2, Michels A.2
1Luxembourg Researchers Hub a.s.b.l., Luxembourg
2University of Luxembourg, Luxembourg
Abstract
This study presents a detailed experimental and computational investigation into the grain growth rates of metallic tungsten during hydrogen reduction of tungsten trioxide. Using advanced techniques, including synchrotron nano-tomography, we characterized the transient grain size distribution (GSD) and morphology evolution of tungsten grains. The results highlight the significant role of water vapor in enhancing grain growth through chemical vapor transport (CVT) of WO₂(OH)₂ and its deposition onto metallic tungsten. These experimental observations were then utilized to develop a high performance computational (HPC) model, simulating the volatilization and deposition processes. This allowed us to derive key kinetic and physical data governing tungsten grain growth during reduction. By integrating HPC simulations with state-of-the-art experimental data, we offer new insights into the microstructural evolution and transient growth mechanisms of tungsten, with implications for optimizing material synthesis in industrial applications. Overall, the findings provide a predictive framework, for understanding tungsten grain growth during hydrogen reduction, applicable to broader metallurgical processes.
13:50 SIM07-A 3
The Effects of Dihedral Angle on Distortion and Grain Segregation during Liquid Phase Sintering of Tungsten Heavy Alloys
Johnson J.1, German R.2
1Novamet/Ultra Fine Specialty Products, USA
2San Diego State University, USA
Abstract
Liquid phase sintering results in rapid densification of engineered components produced from powders, but excess liquid leads to distortion and microstructural segregation. Systems with higher dihedral angles, such as W-Cu, resist slumping at much higher liquid volume fractions than systems with lower dihedral angles such as W-Ni-Fe and W-Ni-Cu. Distortion of W-Ni-Fe and W-Ni-Cu liquid phase sintered under microgravity conditions with liquid contents ranging from 6 to 48 vol. % is investigated and compared to W-Cu with liquid contents ranging from 14 to 83 vol. %. The resulting microstructures are quantitatively analyzed to determine average values for solid volume fraction, grain size, connectivity, and contiguity. Empirical equations are developed to link these microstructural parameters with the three-dimensional coordination number. Critical values of connectivity, coordination number, solid volume fraction, and contiguity that prevent slumping and grain segregation are defined as functions of the dihedral angle.
14:10 SIM07-A 4
Multi-physics Simulation Based Optimization of Refractory Metal Laser Powder Bed Fusion Components for Energy Efficient High Temperature Furnaces
Leitz K.-H.1, Schasching M.1, Valentini B.1
1Plansee SE, Austria
Abstract
High temperature vacuum furnaces typically have operation powers of several hundred kilowatts. In general, they are equipped with a fast cooling system to realize the cooling rates required for heat treatment processes. The inlet gas nozzles and gas outlet of the cooling system, currently designed as holes in the shielding, are major sources of energy losses.
In the development of energy efficient refractory metal hot zones for high temperature vacuum furnaces at PLANSEE SE multi-physics simulations were applied for the design and optimization of thin-walled gas permeable structures shielding thermal radiation. Before manufacturing, thermal, fluid dynamical and thermo-mechanical models were used to evaluate shielding efficiency, flow resistance and mechanical load capacity of inserts for the gas nozzles and the gas outlet of refractory metal hot zones. The developed structures were fabricated by laser powder bed fusion of molybdenum and evaluated in a test furnace with respect to power consumption, temperature homogeneity and cooling efficiency. At this, significant energy savings at an improved temperature homogeneity without a loss of cooling efficiency could be demonstrated.

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14:50 CAT15-B 1
Exploring Microstructural Phenomena in WC–Co Cemented Carbides via Advanced Microscopy
Ringer S.1, Chen H.1, Zhou R.1, Czettl C.2, Weirather T.2, Pachlhofer J.2, Mueller P.2, Teppernegg T.2, Useldinger R.3, Primig S.4
1The University of Sydney, Australia
2CERATIZIT Austria GmbH, Austria
3CERATIZIT Austria GmbH, Australia
4The University of New South Wales, Australia
Abstract
Recent advances in microscopy such as aberration-corrected (scanning) transmission electron microscopy (S/TEM), energy-dispersive X-ray spectroscopy (EDXS), transmission Kikuchi diffraction (TKD), and atom probe tomography (APT)–have enabled researchers to probe the structural and compositional characteristics of WC–Co cemented carbides at the atomic level. These advanced methods enable detailed exploration of microstructural phenomena in WC–Co cemented carbides, providing critical new insights into their mechanical properties and performance.

In this talk, we will present recent findings on several topics: the effect of WC/WC grain boundary misorientation on local hardness; the accurate identification of the pristine Co phase; the role of Ru in enhancing hardness; and the impact of cryogenic treatment on hardness and fracture toughness. We will also share other recent advances relevant to the hardmetals industry: the species-specific quantification of short-range order (clustering) via atom probe, and alloy design opportunities arising from additively manufacturing.
15:10 CAT15-B 2
Quality assessment of cemented carbides by measuring the Seebeck coefficient
Mari D.1, Degeneve L.1, Gaju Musabi R.1, Tkalcec-Vaju I.1
1EPFL, Switzerland
Abstract
The measurement of the thermoelectric power, also known as Seebeck coefficient, is a very sensitive method allowing the evaluation of composition variations in metals and alloys. In this paper we examine a wide range of cemented carbides with a cobalt binder. The materials had different WC grain size ranging from sub-micron size to 4 µm size and Co content ranging from 6wt% to 23wt%.  The Seebeck coefficient against copper was measured in all samples. The results show that it varies strongly as a function of the inverse of the WC grain size. The sensitivity to cobalt content or composition is less striking, even if, for wide variations of Co content, an increasing trend is observed.  The measurement of the thermoelectric power may represent a new method for quality control in cemented carbides.
15:30 CAT15-B 3
Study hard-coatings using advanced electron microscopy methods
Chen Z.1, Huang Y.1, Zhang Z.1
1Erich Schmid institute of materials science, Austrian Academy of Sciences, Austria
Abstract
The industrial application of transition metal nitride hard coating requires an in-depth understanding of the structures and their correlations to properties. This paper summarizes our recent atomic-resolution studies concerning transition metal nitride hard coatings.
The extended high-resolution transmission electron microscopy (HRTEM) study on the TaN/TiN multilayer reveals that the dissociation of full dislocation results in creating a network of stacking faults and the formation of Lomer-Cottrell lock arrays inside the TaN layer, which leads to strengthening the TaN/TiN multilayer [1] significantly. Using low-loss and core-loss spectra, we can map the multilayer's mechanical properties (bulk modulus) at the nanometer scale [2]. We also found that the presence of oxygen impurities causes a remarkable reduction of the bulk modulus of rs-CrN while having no significant effect on the bulk modulus of the stable wurtzite structure wz-AlN layers [3]. In addition, we observed a surprising atomic-scale intermixing phenomenon in the nanoscale TiN/AlN multilayer [5]. We found a new ceramic deformation mechanism in WN/TiN hard coating, i.e., unit-cell disturbance [6].
[1] Yong Huang et al., Acta Materialia, 255, 119027 (2023).
[2] Zaoli Zhang et al., Acta Materialia, 194, 343(2020).
[3] Zhuo Chen et al., Nature  Communication, 14, 8387 (2023).
This work is financially supported by the Austrian Science Fund (FWF P33696-N). The authors would like to thank Prof. Christian Mitterer (Montanuniversität Leoben) and Paul Heinz Mayrhofer (Technische Universitaet Wien).
15:50 CAT15-B 4
In-situ synchrotron X-ray diffraction investigation of microstructure evolution in Cr-doped cemented carbide during high-temperature deformation
Yildiz A.B.1, Böhm A.2, Koko A.3, Reinhard C.4, Michalik S.5, Borgh I.2, Olovsjö S.6, Kritikos M.7, Lindberg F.7, Weidow J.8, Norgren S.9, Hedström P.10
1Scatterin AB, Sweden
2Sandvik Mining and Rock Solutions, R&D Rock Tools, Sweden
3National Physical Laboratory, United Kingdom
4The University of Manchester at Harwell & 5 The University of Manchester, Faculty of Science and Engineering, United Kingdom
5Diamond Light Source Ltd., United Kingdom
6Seco Tools AB, R&D Materials and Technology, Sweden
7Sandvik Coromant R&D, Sweden
8Department of Physics, Chalmers University of Technology, Sweden
9Sandvik Coromant, Sweden
10KTH Royal Institute of Technology, Sweden
Abstract
During machining and drilling operations, the temperature of cemented carbide tools can reach as high as 1000 °C, and the material experiences high mechanical stresses as well. Previous investigations by the authors have shown that Cr additions can increase the high-temperature resistance to plastic deformation and result in up to three times longer cutting tool life. In the current study, we present how high-energy synchrotron X-ray diffraction (S-XRD) can be used to probe the microstructure evolution in Cr-doped cemented carbide during high-temperature deformation under compressive load using an electro-thermal mechanical testing (ETMT) device as sample environment. Under mimicked service conditions, i.e. up to 1000 °C and 1 GPa compressive load, S-XRD enabled us to acquire diffraction patterns with sufficient statistics from WC and Co-rich binder phase with 3 s/pattern time resolution. The analysis of the acquired S-XRD patterns provided quantitative information on strain, stress, and microstructure evolution—such as dislocation density—in the WC and binder phases. This enabled us to develop an improved understanding of the mechanisms behind improved creep resistance in Cr-doped cemented carbide.

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14:50 NF99-A 1
Low activation WC and WB for shielding applications in compact fusion devices
Rigby-Bell M.1, Emmanuel M.1, Sharp J.2, Harada M.3, Wade-Zhu J.1, Jarvis D.4, Van den Blik R.4, Mellor R.4, Sandoval D.5, Tarres i Puit E.5
1UKAEA, United Kingdom
2School of Computing and Engineering, University of Huddersfield, United Kingdom
3Centre for Nuclear Engineering, United Kingdom
4VSCA AS, Norway
5Hyperion MT, Spain
Abstract
Compact spherical tokamaks have severely limited space for shielding - required to protect the magnets from intense neutron radiation. Thus, high-efficiency neutron shielding materials are needed, with high thermal conductivity; radiation damage tolerance; low lifecycle activation; resistance to transmutation; and high density.
Tungsten carbide (WC) and borides (WB) have high neutron attenuation across a broad energy spectrum. Combined with low activation Fe-Cr based binders, they are good shielding candidates. However, the effects of radiation damage on the properties of WC and WB are poorly understood.
In this work, we have conducted high energy light and heavy ion irradiations on grades of cemented WC and WB to a range of doses up to 50 dpa across an elevated temperature range. Ambient and elevated temperature and nanoindentation have been used to measure hardness and elastic modulus, with single cantilever bending tests to measure strength and fracture toughness in bulk samples. Combined with microstructural, chemical and radiation damage defect characterisation, these properties are used to understand and predict irradiation-induced changes in performance.
15:10 NF99-A 2
Assessing He-irradiation Damage in High-Entropy Thin Films for Plasma-Facing Applications like Fusion Reactor First-Walls
Mayrhofer P.1, Astecker T.1, Hosemann P.2, Polcik P.3, Kirnbauer A.1
1TU Wien, Austria
2University of California Berkeley, USA
3Plansee Composite Materials GmbH, Germany
Abstract
We studied magnetron-sputtered high-entropy (Hf,Ta,Ti,V,Zr)-based nitride, carbide, and diboride thin films for their potential in first-wall applications of fusion reactors. The films were subjected to localized helium-irradiation (25 keV, fluences ranging from 0.5×10¹⁷ to 5×10¹⁷ ions/cm²) at ambient temperature. All films showed a stable single-phase structure—nitrides and carbides in a face-centered cubic, and diborides in a hexagonal close-packed structure—without signs of amorphization. Despite having the same metal-contributions, swelling-behaviors varied, with the carbide swelling like tungsten, but the diboride and nitride only swelled 11.7% and 10.7% at He-dose of 5×10¹⁷ ions/cm². The nitride’s larger grain size helped reduce swelling through He-release at grain boundaries. Their mechanical properties differ pre-irradiation, with hardnesses ranging from 26.9 GPa (nitride) to 38.9 GPa (diboride), and post-irradiation degradation was most severe in the carbide, which provides lowest fracture toughness (Kᵢc = 2.5 MPa√m). The diboride's superior resistance (Kᵢc = 3.5 MPa√m) leads to its highest robustness against He-induced damage among these films. This study highlights the importance of microstructure in enhancing irradiation resistance for high-entropy ceramics in extreme environments.
15:30 NF99-A 3
Development and characterization of minor carbon-doped tungsten by chemical vapor deposition for future fusion devices
Binyou Y.1, Jiupeng S.2, Zexi H.1, Baozhi L.1, Zhaohui H.1
1Xiamen Tungsten Co., Ltd., China
2School of Materials Science and Engineering, Xihua University, China
Abstract
Chemical vapor deposition tungsten (CVD-W) is considered as one of the promising materials for plasma facing components due to its high purity, thermal conductivity and grain structure stability at ultra-high temperature. However, as the thickness of CVD-W increases to mm-grade, poor mechanical properties caused by coarse columnar microstructure gained more concerns.
A novel minor carbon-doped CVD-W (MCCVD-W) was developed by activated-propane participating in the reduction reaction of tungsten hexafluoride and hydrogen. A refined columnar grain structure was obtained as the carbon content of MCCVD-W ranged from 65 to 168 ppm, without significantly sacrificing density and thermal conductivity of CVD-W.
TEM analysis showed nano-scale hexagonal W2C was formed in cubic W lattice, which may be responsible for significantly refining of columnar grain and improving of mechanical strength. Although the decomposition of W2C may affect stability of microstructure, EBSD analysis showed the microstructure of MCCVD-W remained stable below 1950 ℃. Additionally, no macro cracks were observed in ITER-like divertor mono-block fabricated by MCCVD-W after 1000 cycles thermal fatigue test of 20 MW/m2, 15s on / 15s off.
15:50 NF99-A 4
Microstructural examination of neutron irradiation induced defects in tungsten
Klimenkov M.1, Rieth M.1, Jaentsch U.1, Van Renterghem W.2, Terentyev D.2
1Karlsruhe Institute of Technology, Germany
2SCK CEN - Belgian Nuclear Research Centre, Belgium
Abstract
ungsten (W), which has a number of advantageous properties such as high melting temperature, excellent thermal conductivity, high strength and low sputtering yield, is considered a promising plasma-facing material for future fusion reactors.
An important factor in assessing the applicability and lifetime of plasma-facing components is their microstructural response to neutron irradiation.
For this propose, ITER grade W was neutron irradiated in the BR2 Material Test Reactor (Mol, Belgium) at a temperature between 600°C and 1200°C up to a damage dose of 0.8 dpa (displacement per atom). The microstructure of the irradiated material was analyzed using a transmission electron microscope (TEM).
The study includes the identification and quantitative analysis of radiation-induced defects such as voids and dislocation loops as well as a comprehensive analytical investigation of Re- and Os-segregation on defects. Dose-dependent changes of the size and number density of voids and loops were also shown. This study enables not only the prediction of the lifetime of W components, but also the experimental validation of the theoretical modelling of radiation-induced defects in W.
16:10 NF99-A 5
Engineering damage tolerant tungsten boride neutron shielding driven by radiation damage studies
Humphry-Baker S.1, Zagyva T.1, Hasegawa M.1, Davidson J.1
1Imperial College London, United Kingdom
Abstract
For compact fusion reactors to operate continually, high performance radiation shielding materials must be developed. The tungsten borides, specifically WB and WB2, are highly effective materials for this application. This presentation focusses on their irradiation damage, which at moderate temperatures leads to point defect formation and associated swelling. Samples are irradiated with helium ions at 300-700 °C and characterised afterwards using grazing-incidence X-ray diffraction and transmission electron microscopy. At all temperatures defect storage rates in WB2 exceed those in WB. At 300 °C, defect storage is so strong in WB2 that it amorphises, causing volume changes of ~5 %. As temperature increases, the defect induced swelling monotonically decreases for both compounds. Due to their anisotropic crystal symmetry, both materials swell anisotropically. Understanding this is important as it can lead to mis-match strains at the grain boundaries, which can drive spontaneous cracking. Our work is therefore driving efforts to develop materials with engineered grain boundaries (e.g., though grain alignment, refinement, and ductile phase reinforcement). Ongoing processing efforts to develop such structures is described.