Abstract
The liquid phase sintering mechanisms of Mo2NiB2 base hard alloys were studied for three alloy compositions. The MozNiB2 boride phase exhibited the orthorhombic or tetragonal crystal structure depending on alloy composition and processing temperature. The orthorhombic M3B2 (M: Mo, Ni) was formed by a solid state reaction prior to liquid phase formation associated with the quasi-eutectic reaction between the orthorhombic M3B2 and the Ni base metallic phase in a Mo-Ni-B alloy. Full densification was achieved by the quasi-eutectic liquid phase.
The orthorhombic M3B2 transformed to the tetragonal M3B2 with increasing temperature in the solid state for Cr and V containing Mo-Ni-B alloys, where Cr and V were mainly distributed in the M3B2 phase. The quasi-eutectic liquid phase also lead to full densification in these alloys.
