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

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 mu m and then spark plasma sintering the blended powders. We investigated the microstructures of the specimens using SEM-EDS and TEMEDS, 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.