TiN-CoおよびTiN-WC-Co系の液相焼結

Abstract

1) A mutual solubility of titanium nitride and cobalt was observed in the sintering of the TiN-Co system at 1600°-1800°C.2) In the sintering of the TiN-WC-Co system, in addition to the above fact, tungsten carbide seemed to be dissolved into the other two phases, in the way that W atoms were mainly dissolved into the cobalt phase whereas C atoms were dissolved into the titanium nitride phase.3) The microstructure of TiN-10wt% WC-20wt% Co alloy was analysed by E. P. M. A. and I. M. A.. Grains were titanium nitride phase and a binder phase was cobalt phase.4) The solid skelton forming for grains during sintering for the binary systems was observed and it is indicating the incomplete wetting of tungsten carbide to this binary alloy resulted in an improvement of the wettability of titanium nitride phase to the binder phase.5) The solution-precipitation process in the sintering for the TiN-WC-Co system was controlled by the solution reaction of granular particles at solid-liquid boundaries.6) The maximum mechanical strength obtained for the TiN-WC-Co ternary alloys at any sintering conditions was essentially higher than that for the TiN-Co binary alloys.