Abstract:Effects of VC/Cr₃C₂ on the microstructure and mechanical properties of Ti(C,N)-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning electron microscopy in combination with energy dispersive spectrometry. Mechanical properties, such as transverse rupture strength, hardness and fracture toughness, were measured. The results show that there are black core−grey rim structure and white core−grey rim structure in the microstructure. The grains become fine due to the VC/Cr₃C₂, and the grains of cermet added with 0.75VC/0.25Cr₃C₂ are refined most remarkably. The black core becomes finer with the increase of VC addition and rim phase becomes thicker with the decrease of Cr₃C₂ addition. The porosity increases with the increase of VC addition in VC/Cr₃C₂. Compared with the cermet free of VC/Cr₃C₂, the transverse rupture strength and hardness of cermets with VC/Cr₃C₂ are both improved, and the maximum values are both found for the cermet with 0.25VC/0.75Cr₃C₂. The fracture toughness can be effectively promoted by adding VC/Cr₃C₂ with an appropriate ratio of VC to Cr₃C₂, and the maximum value is found for the cermet with 0.5VC/0.5Cr₃C₂.

Key words: Ti(C, N)-based cermet; VC; Cr₃C₂; microstructure; mechanical properties