Microstructure, mechanical properties, oxidation behaviors, and cutting performance of TiC0·5N0.5-X (X: W, Mo) cermet specimens prepared by spark plasma sintering

Abstract In this study we prepared a series of TiC0·5N0.5-W and TiC0·5N0.5-Mo cermet specimens with different W and Mo content by blending TiC0·5N0.5, W, and Mo powders with particle sizes of less than 1 μm and then spark plasma sintering the blended powders. We investigated the microstructures of the specimens using SEM-EDS and TEM-EDS, and examined their mechanical and oxidation properties at high temperatures. The microstructures of the specimens were unique: each Ti(C, N) particle in the TiC0·5N0.5-W cermet was surrounded by a W-rich phase, and each Ti(C, N) particle in the TiC0·5N0.5-Mo cermet was surrounded by an Mo-rich phase. The TiC0·5N0.5-(20–70) mass% W and TiC0·5N0.5-(20–40) mass% Mo cermet specimens exhibited a much higher microvickers hardness than the TiC0·5N0.5 and HTi10 (ISO K10) WC-Co cemented carbide specimens in a temperature range from room temperature to 1273 K. Further, the TiC0·5N0.5-(50–70)mass% W and TiC0·5N0.5-(20–40)mass% Mo cermet specimens exhibited much better oxidation resistance than the HTi10 specimens at 973 K. Lastly, the cutting tip specimens prepared using the TiC0·5N0.5-70mass% W and TiC0·5N0.5-60mass% Mo cermet specimens exhibited much higher wear resistance than commercially available HTi10 cutting tips when used to cut S32750 super-duplex stainless steel and Inconel 718 alloy round bars, two materials known for their high cutting resistance.