Microstructure and properties of ultra-fine TiC0.7N0.3 cermet

Ti(C, N) based cermet with an average particle size less than 0.5 μm is fabricated by using ultra-fine TiC0.7N0.3 with average particle size less than 0.2 μm. Cermets made up of ultra-fine TiC0.7N0.3 powders have higher hardness and strength than those of conventional powders. In order to find out the reason for the hardness and strength increase, XRD, SEM, EPMA and TEM are employed to observe the microstructures of the two cermets. The results show that the two cermets have the same constituent phases, namely TiC0.7N0.3, (Ti, Mo, Ta, W) (C, N) and solid solution Co(Ni). Solid solution (Ti, Mo, Ta, W) (C, N) is the hard phase and solid solution Co(Ni) is the binder phase. The core–rim microstructure is the result of alloy elements distributing in the outer part of Ti(C, N) particles during the process of diffusion. There are dislocations and twin crystals in solid solution (Ti, Mo, Ta, W) (C, N), and a kind of precipitation phase appears in solid solution Co(Ni) which is unknown, rather fine and coherent with Co(Ni) matrix.