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C. Buchegger, J. Langlade, W. Lengauer:
"Interdependencies of Grain-Growth Inhibitor Diffusion in WC-Co Hardmetals";
Poster: 18. Plansee Seminar 2013, Reutte; 06-03-2013 - 06-07-2013; in: "Proceedings", (2013), 1 - 11.

The diffusion behaviour of the grain-growth inhibitors (GGIs) Cr and V in WC-Co hardmetals was analysed. For this purpose diffusion couples of the type GGIs-Co/WC-Co were prepared and sintered at temperatures from 1050 - 1360 °C to get insight into the diffusion characteristics at various sintering stages. The resulting concentration profiles of the GGIs in the WC-Co side of the diffusion couples were measured by electron probe microanalysis (EPMA-WDS). As the diffusion occurs via the Co binder phase it was interesting to investigate the influence of the Co powder grain size on the GGI migration. In addition, the interdependency of V and Cr diffusion and the influence of the presence of Ta - a further common GGI - were studied at various carbon activities in the hardmetal. From these data diffusion coefficients and activation energies were calculated. The microstructure of the hardmetals was characterised with respect to grain size of WC as a function of distance from the WC-Co/GGI-Co interface.

The diffusion behaviour of the grain-growth inhibitors (GGIs) Cr and V in WC-Co hardmetals was analysed. For this purpose diffusion couples of the type GGIs-Co/WC-Co were prepared and sintered at temperatures from 1050 - 1360 °C to get insight into the diffusion characteristics at various sintering stages. The resulting concentration profiles of the GGIs in the WC-Co side of the diffusion couples were measured by electron probe microanalysis (EPMA-WDS). As the diffusion occurs via the Co binder phase it was interesting to investigate the influence of the Co powder grain size on the GGI migration. In addition, the interdependency of V and Cr diffusion and the influence of the presence of Ta - a further common GGI - were studied at various carbon activities in the hardmetal. From these data diffusion coefficients and activation energies were calculated. The microstructure of the hardmetals was characterised with respect to grain size of WC as a function of distance from the WC-Co/GGI-Co interface.

Hardmetal, grain-growth inhibition, diffusion, activation energy, vanadium carbide, chromium carbide, tantalum carbide