Effect of VC additions on the microstructure and mechanical properties of TiC-based cermets

VC is important carbide additive and has a similar crystal structure with TiC. In this study, the effect of adding VC amounts at content levels of 1–8 wt% on the microstructure evolution and mechanical properties of TiC-based cermets is examined. The specimens were characterized by scanning electron microscopy observations, energy-dispersive x-ray spectroscopy analysis, Image-Pro plus statistical analysis, transverse rupture strength tests, and hardness tests. The results show that VC addition is beneficial to promote the liquid-phase sintering process. When the VC addition amount is lower than 4 wt%, added VC mainly distributes in the surrounding outer rims. With increasing VC additive, the black cores are slowly dissolved and the average thickness of rims increases slightly. Many dimples exist in the fracture morphology and the strength increases gradually. Furthermore, when the VC content increased to 6–8 wt%, a part of VC is solid-dissolved with TiC, black cores with large grain appear and surround with thick outer rims. The large core-rim structure exhibits transgranular fracture mode and causes the toughness decreased. (paper)