Technical Program

Status: 3 June, 2022
Monday, 30 May, 2022
09:40 - 10:20
Opening Ceremony
Location: Walter Schwarzkopf Hall
10:20 - 12:20
Opening Session
Location: Walter Schwarzkopf Hall
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10:20 OS 1
Plansee Seminar's 1952-2022 - A view on a very special congress
Danninger H.1
1Vienna University of Technology, Austria
11:00 OS 2
Molybdenum and Tungsten, the greener Metals?
Walser H.1
1-, Austria
11:40 OS 3
An attempt to do an outlook on the P/M Hard Metal industry after two years of world pandemic and present unstable times in Europe
Norgren S.1
1Sandvik AB, Lund University, Sweden
12:20 - 13:00
Lunch Break
Location: Walter Schwarzkopf Hall
13:00 - 14:40
Hard Materials - Materials 1
Location: Walter Schwarzkopf Hall
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13:00 HM 1
Grain growth inhibition in V-doped and Ti-doped WC-10wt%Co cemented carbides at low doping concentrations
Gren M.1, Fransson E.1, Larsson H.2, Weidow J.1, Blomqvist A.3, Norgren S.3, Wahnström G.1
1Chalmers University of Technology, Sweden
2Royal Institute of Technology, Sweden
3Sandvik Coromant R&D, Sweden
It is important to control the growth rate of WC grains during sintering WC-Co cemented carbides. To this end, the material is commonly doped with grain growth inhibitors such as vanadium, chromium and titanium. It is well established that thin interfacial structures with a high dopant content can be formed at phase boundaries in the material.

Here, we present theoretically derived phase diagrams for these thin interfacial structures, known as complexions, using first-principles techniques. Possible non-stoichiometries and various temperature dependent effects are taken into account in a proper way. The result is presented for vanadium and titanium doped materials, both for solid state and liquid phase sintering conditions.

For low dopant concentrations dopant-rich interfacial structures cannot form, but still reduction of the grain growth rate is observed. By detailed investigation of the step mobility we show, for vanadium and titanium, that local segregation of atoms to step edges is present and thereby reduce the step mobility.
13:20 HM 2
Towards Co-free hard materials: a designing methodology and case study
Gordo E.1, de Nicolas M.1, Llanes L.2
1University Carlos III of Madrid, Spain
2Universidad Politécnica de Cataluña, Spain
Avoiding the use of Co is one of the main goals in searching alternative compositions for hardmetals. However, it introduces difficulties in processing and involves a range of unknown mechanisms influencing the final microstructure, properties, and reliability of material produced. As a help to face this issue in this study a systematic methodology is used that comprises the design of composition by thermodynamic simulation combined with thermal analysis; high-temperature wettability studies; optimization of processing parameters, and final characterization. A case study based on FeNiCr metal binder combined with Ti(C,N) and WC as hard phases is presented. The results include the role of Cr and C in the wetting behavior of the metal phase with the two ceramic phases and its influence on microstructural features such as grain size and distribution. Properties such as hardness, fracture toughness, and corrosion resistance are also presented. A comparison of this satisfactory-wetting system with a non-satisfactory-wetting system such as FeCrAl is discussed, and the influence of wetting ability in the sintering behavior of both systems is presented.
13:40 HM 3
Liquid phase assisted synthesis of high entropy carbide cermets from monocarbides as starting materials.
Anwer Z.1, Vleugels J.1, Huang S.1
1KU Leuven, Belgium
Two nickel bonded high entropy carbide (HEC) systems with five and six equimolar monocarbides i.e. (Nb,Ti,V,W,Ta)C & (Nb,Ti,V,Mo,W,Ta)C were respectively synthesized by pressureless liquid phase sintering of carbide starting powder mixtures at 1420°C for 90 min. The microstructure of the fully densified cermets, consisted of a FCC high entropy carbide solid solution embedded in a nickel binder alloy, indicating that all the monocarbides were dissolved into each other and formed a core-rim structure of mixed carbides. Phase analysis was carried out using XRD and SEM, whereas electron probe microanalysis (EPMA) was used for phase compositional analysis. The experimental results showed good compliance with the prognosticated thermodynamic calculations, using ThermoCalc software. The (Nb,Ti,V,W,Ta)C based cermet has a higher Vickers hardness of 15.08 ± 0.16 GPa and an indentation fracture toughness of 8.3 ± 0.1 MPa.√m. This study successfully demonstrated the production of HEC based cermets following the conventional industrial manufacturing regime.
14:00 HM 4
Hot hardness modelling of cemented carbides and cermets
Lamelas Cubero V.1, Bonvalet Rolland M.1, Walbrühl M.2, Borgenstam A.1
1Kungliga Tekniska Högskolan (KTH), Sweden
2QuesTek Europe AB., Sweden
The excellent performance of cemented carbide machining tools relies strongly on their high hardness. Thus, numerous models have been developed correlating hardness to microstructural parameters such as carbide grain size or binder volume fraction among others. Despite their good predictions, these models are limited and have mostly been focused on room temperature hardness of the WC-Co systems. Nonetheless, during operation, tools can reach temperatures of about 1000°C causing considerable softening of the material. This fact, combined with the introduction of refractory metal carbonitrides (γ-phases) to reduce this drop in mechanical properties makes the applicability of state-of-the-art models more challenging.
Framed in an Integrated Computational Materials Engineering (ICME) approach, a model describing the change in the cemented carbides and cermets hardness with temperature, is proposed. The model, an extension and integration of previous models, is built to be generic and thus applicable to different binder chemistries through:
• accounting for the effect of temperature on the hardness of WC and γ-phases.
• quantifying the impact on microstructural changes such as lamellae or cavity formation on hardness.
14:20 HM 5
Ultra-high Hardness and Tough Metallic Alloys
Guisard Restivo T.A.1, Guisard Restivo G.M.1, Pires Nonato R.B.2, Wellington A.P.3, Ortiz Ladwig M.G.2, Belchior A.2
1Thermophysical Lab and University of Sorocaba, Brazil
2University of Sorocaba, Brazil
3IFSP – Federal Institute of Sao Paulo, Brazil
Multi-component Metallic Diamond alloys (Diamoy) are a new alloy class holding extreme hardness and strength properties while showing reasonable toughness. Diamoy alloy formulations were derived from the rather simple “Lattice Occupancy Alloy Project” which employs strong body centred cubic structure promoters and medium to high cooling rates from cast melts. As-cast plasma melted alloys are composed by 6 to 9 different elements at mole fractions from 1/9 to 3/9. The main alloy elements are Cr, Fe and Nb, together with Ti, Ta, W and other elements over different formulations. In the present article, Diamoy-4, -6 and -7 alloy bars and plates were casted and annealed in order to be formed by rolling and to increase ductility and toughness through thermomechanical treatments. The alloys respond to carburizing treatments where very thin carbides are formed. Vickers hardness values from 14 to 25 GPa were attained for as-cast and treated alloys, while the facture toughness were measured from 8 to 20 MPa.m1/2. X-ray diffraction profiles and SEM-EDS reveal 2 or 3 phases which were indexed to body centred cubic structure, being the phases composition very close to each other. Annealing treatments at 1200-1300°C were found to even increase the hardness suggesting better homogenization. Tensile strength in excess to 3000 MPa and ductility above 10% were achieved. Diamoy-4 alloy insert has shown similar wear performance for turning steel compared to WC-Co commercial cemented carbide, with further advantage of no crater formation. Diamoy cast alloys can be readily powdered to generate a product for pressing and sintering to sound parts. Metallic Diamond Alloys are promised materials for severe application conditions, aiming to defy the strength-ductility paradigm.
14:40 - 15:00
Location: Walter Schwarzkopf Hall
15:00 - 16:50
Refractory Metals - Materials 1
Location: Walter Schwarzkopf Hall
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15:00 RM 1
Enhancing mechanical properties of ultra-fine grained tungsten via grain boundary segregation engineering - KEYNOTE
Kiener D.1, Doppermann S.1, Wurster S.2, Jakob S.1, Alfreider M.1, Schmuck K.1, Bodlos R.3, Romaner L.1, Clemens H.1, Maier-Kiener V.1
1Montanuniversität Leoben, Austria
2Erich Schmid Institute of Materials Science, Austria
3Materials Center Leoben, Austria
Tungsten, while showing many favorable properties, faces challenges in high-performance applications due to its brittle nature. One strategy to improve strength and toughness in tungsten is to refine the grain size down to the ultra-fine grained regime. However, as the grain size is reduced, the fraction of grain boundaries that provide easy paths for crack growth increases, thereby limiting the gain in ductility. Therefore, strengthening the grain boundaries is of great importance if one wants to tap the full potential of this material. Using ab-initio calculations, potential grain boundary cohesion enhancing doping elements were identified, and doped ultra-fine grained tungsten samples were fabricated and characterized extensively using small-scale testing techniques. We found that additions of boron and hafnium improve the mechanical properties of tungsten remarkably. Furthermore, an additional low-temperature heat treatment of the boron-doped sample promotes grain boundary segregation, enhancing the properties even further. Thus, in this work we provide an effective pathway of improving mechanical properties in ultra-fine grained tungsten using grain boundary segregation engineering.
15:30 RM 2
Tungsten-Based Bcc-Superalloys: Thermal Stability and Ageing Behaviour
Knowles A.1, Parkes N.1, Dodds R.2, Dye D.2, Hardie C.3
1University of Birmingham, United Kingdom
2Imperial College, London, United Kingdom
3Culham Centre for Fusion Energy, Culham, United Kingdom
Here, we have investigated a concept of “W superalloys”, analogous to Nickel-superalloys but instead exploiting a tungsten base for enhanced high temperature performance. This strategy involves reinforcing bcc-W by second phase B2 TiFe intermetallic compound to give a “bcc-W superalloy” microstructure. Through investigation of phase equilibria, thermodynamic modelling, characterisation and mechanical properties (500 MPa at 1000°C), we demonstrate the capability of ternary W-Ti-Fe tungsten-based bcc-superalloys toward a new class of high temperature materials.
15:50 RM 3
Microstructure, high-temperature strength and oxidation resistance of spark-plasma sintered compact of gas-atomized MoSiBTiC powder
Yoshimi K.1, Arai H.1, Umeda K.1, Nan X.1, Ida S.1, Sekido N.1
1Tohoku University, Japan
MoSiBTiC alloy powder with a nominal composition of 65Mo-5Si-10B-10Ti-10C in at% was produced by an electrode induction melting gas atomization technique. Sound MoSiBTiC alloy compacts with a relative density of about 100% was obtained by the spark-plasma sintering (SPS) method. Reflecting the rapid solidification effect of the gas atomization, the microstructure of the compacts was refined by more than an order of magnitude as compared with the arc-melted one. The high-temperature strength of the MoSiBTiC alloy compact examined by compression test at a temperature of 1400 °C and a strain rate of 10^(-4) /s was about 800 MPa even at 1400 °C, which is about 100 MPa higher than that of the arc-melted one, despite the microstructure refinement. With respect to oxidation, the compact showed more intense oxidation due to pesting at 800 °C, but in contrast it was well-improved at 1100 °C. These oxidation resistance change of the MoSiBTiC alloy compact is considered to be caused by the microstructure refinement.
16:10 RM 4
Development of Cr-rich Cr-Si-Fe and Cr-Si-Ni alloys for structural high temperature applications
Ulrich A.S.1, Kerbstadt M.1, Galetz M.C.1
1DECHEMA-Forschungsinstitut, Germany
Due to their high melting point and good oxidation resistance Cr-rich Cr-Si alloys are promising candidates for structural high temperature applications with working temperatures beyond these of Ni-based superalloys. However, the main drawbacks still are the embrittlement by Cr2N formation and high ductile to brittle transition temperatures (DBTT).
Therefor this work shows the effect of alloying Cr-Si-alloys with the third elements Fe and Ni and targets especially the investigation of the microstructure and precipitation fracture. Varied compositions are manufactured by arc-melting and subsequent heat treatment at 1200°C, which enables controlled precipitation hardening by the Cr3Si-A15 phase. The microstructural development depending on composition and annealing process is analyzed by SEM, EPMA, XRD, and hardness measurements.
Ni can cause the effect of solution softening in Cr and increases the low-temperature ductility as a result. For Fe it is shown, that it stabilizes the two-phase structure consisting of nitration resistant A15 phase and Cr. Oxidation exposures at 1200°C in synthetic air indicate that Fe additions up to 5 at.% increase also the nitridation resistance of Cr.
16:30 RM 5
Strain-rate Effects on Recrystallization of Molybdenum-Based MZ-17 Alloy
Sandim H.1, Souza F.I.2, Knabl W.3, Kestler H.3
1University of São Paulo, Brazil
2University of Sao Paulo, Brazil, Brazil
3Plansee SE, Austria
Warm pressing was performed on samples of the Mo-based alloy MZ-17 (Mo-1.7%ZrO2) to about 60% reduction in height at 1000 and 1100oC to investigate the effects of strain rate and deformation temperature on recrystallization. Warm deformation was performed using a deformation dilatometer in cylindrical specimens at varying strain rates (10-1-10 s-1) followed by fast cooling. Single-peak stress-strain curves can be noticed for all testing conditions. As-pressed microstructures were imaged at the center of the samples where plastic flow is more uniform using electron backscatter diffraction (EBSD) to distinguish recovered and recrystallized grains and electron channeling contrast imaging (ECCI) to visualize the dislocation structures. In all tested temperatures and strain rates, recrystallization was only partial with increasing volume fraction with deformation temperature. Important orientation effects on recrystallization behavior can be noticed because of the coarse-grained starting microstructure. There is microstructural evidence of three diffusion-controlled restoration mechanisms acting during warm deformation; i.e., dynamic recovery, (meta)dynamic recrystallization and particle stimulated nucleation (PSN) of recrystallization.
16:50 - 16:50
End of sessions
Location: Walter Schwarzkopf Hall