Influence factors and microstructure evolution during preparation of nanocrystalline (Ti, W, Mo, V)(C, N)-Ni composite powders

摘要

Nanocrystalline (Ti, W, Mo, V)(C, N)-Ni composite powders with crystalline size of about 35 nm were synthesized at 1300 deg C from oxides by a simple and cost-effective route which combines traditional low-energy milling plus carbothermal reduction-nitridation techniques. Influence of main technological parameters was investigated by X-ray diffraction, and microstructure of the milled powders and reaction products was studied by scanning electron microscopy. The results show that the phase evolution of TiO_2 follows TiO_2 -> Ti_3O_5 -> Ti(C, N), and (Ti, W, Mo, V)(C, N)-Ni composite powders with higher nitrogen content and smaller crystalline size can be produced by introducing high nitrogen pressure. By contrast with high nitrogen pressure, high synthesizing temperature and long isothermal time can contribute to dissolution of W, Mo and V atoms into Ti(C, N). In addition, synthesizing temperature has a significant effect on the microstructure evolution of (Ti, W, Mo, V)(C, N)-Ni composite powders.