Microstructure evolution and mechanical properties of (Ti0.93W0.07)C-xWC-20Ni cermets

The microstructure and mechanical properties of (Ti0.93W0.07)C-xWC-20Ni cermets were investigated to determine the effect of WC addition on the Ti-based solid solution cermet, (Ti0.93W0.07)C-20Ni. (Ti0.93W0.07)C-20Ni exhibited a homogeneous microstructure with no core-rim structure; however, a core-rim structure was observed with the addition of WC. The carbide size decreased sharply with the addition of 15 wt.% WC. After composition, very small coreless carbide (VSCC) particles abruptly emerged in the microstructure. These particles might be formed by homogeneous nucleation during the final stage of sintering and cooling after the outer rim formation period. With increasing WC addition, the hardness remained constant, whereas the toughness decreased. Compared with Ti(CN)-based cermets with similar compositions, the hardness and toughness of (Ti0.93W0.07)C-xWC-20Ni cermets exhibited higher values. The refined microstructure of Ti-based solid solution cermets is considered to be responsible for the superior mechanical properties. (C) 2010 Elsevier B.V. All rights reserved.