Microstructure and mechanical properties of WC modified NbC-Ni cermets

The influence of up to 15 vol% WC addition to Ni bonded NbC cermets was assessed by conventional pressureless liquid phase sintering in vacuum for 90 min at 1390 °C. The constituent phases and W distribution in the Ni binder and NbC phase were simulated by thermodynamic modelling. Microstructure and phase analysis using XRD and SEM indicated that the WC-modified NbC based cermets were composed of an (Nb, W)C solid solution cubic phase dispersed in a cubic Ni alloy binder. The variation of the WC content resulted in a clear effect on the final phase constitutions. A residual WC phase was present in the cermets with 15 vol% WC addition. The phase evolution and effect of a different WC content on the solid solution is discussed and the fracture toughness and Vickers hardness is assessed