Effect of VC/Cr3C2 additions on the microstructure, interface structure and mechanical properties of Ti(C,N)-based cermets prepared by in situ carbothermal reduction of nano TiO2

Ti(C,N)-based cermets were prepared by in situ carbothermal reduction of nano TiO2. The effect of VC/Cr3C2 additions on the microstructure, interface structure and mechanical properties of the cermets were investigated using SEM, EDX, and TEM. The microstructure of the cermets was primarily characterized by white core/gray rim grains and black core/gray rim grains, in addition to a small amount of white rimless grains and gray grains without core/rim structure. The addition of VC/Cr3C2 refined the grain size, but the microstructure of the cermets showed little difference with varying VC/Cr3C2 weight ratios. Lattice distortion occurred at the rim/binder and ceramic/binder interfaces, and new orientation relationship and coherency state formed at these interfaces. The transverse rupture strength, hardness and fracture toughness all decreased with increasing VC content, but on the contrary increased with increasing Cr3C2 content. Overall, cermet E with 1.5 wt% Cr3C2 showed the superior comprehensive mechanical properties.