Preparation of fine TiC dispersed alloy by mechanical alloying

Abstract

The formation of ultra fine TiC dispersed alloy by mechanical alloying (MA) and spark plasma sintering (SPS) has been investigated. The composition of Ti_xC_100-x (x=50-80)-20mass%Ni(called cermet) and that of Ti₅₀Ni_x C_50-x (x=20-45) (called NiTi alloy) alloy powder have been synthesized by MA of three kinds of elemental powders. During MA, TiC-Ni consolidation was formed in the vessel for the composition of less than 65at.%Ti mixture. In the case of cermet, after MA, for the composition of more than 70at.% Ti mixture, C and Ni powders were added to MA powder in order to make the total composition of Ti₅₀C₅₀-20mass%Ni cermet. The powder mixture of cermet and NiTi alloy was consolidated by SPS method at 1073K. The size of sintered body was φ15×3mm. This sintered body consisted of TiC, Ni, and Ni-Ti alloy. It was found that the ultra fine TiC (<1000nm) had been formed during SPS process by using Ti₇₅C₂₅-20mass%Ni+C+Ni powder. This ultra fine TiC was dispersed homogeneously in the cermet. In the case of NiTi alloy, the fine TiC was not observed in the sintered sample. And the sample of Ti₅₀Ni_xC_50-x alloy was very brittle.