Abstract
The composite ultrafine particle (UFP) of Ni and TiC was synthesized by arc melting, vaporization and deposition of Ni-Ti-C alloys in an atmosphere of hydrogen-argon mixed gas ("reactive plasma-metal" reaction) at 0.1MPa pressure. The crystal structure, the chemical composition, the morphology and sintering characteristics of obtained UFP were determined by X-ray diffractometry, energy dispersion analysis for X-ray, transmission electron microscopy and dilatometry, respectively.
The UFP obtained from Ni-Ti-C parent alloys containing 60-90 mol%TiC was composed of three phases of Ni, TiC (NaCl type) and Ni3Ti. The TiC concentration of the UFP remarkably deviated negatively from TiC concentration of the parent alloys. The composite UFP consisting of Ni and TiC, whose morphology was dumbbell-like, dice-like or ball-like particles, was found in the obtaind UFP. It is considered that those composite particles are formed during the solidification process of a molten Ni-Ti-C particle condensed in the gas-phase. Dilatometric measurements under hydrogen atmosphere show that the composite UFP has different sintering characteristics from mixed powders of Ni UFP and TiC UFP.
