Reactive synthesis and mechanical properties of Mo2NiB2 based hard alloy

Using three elementary substances, Mo, Ni, and amorphous B powders as raw materials, the ternary boride based hard alloy Mo₂NiB₂–Ni was prepared successfully. The formation mechanism of the ternary phase was verified by XRD. It was indicated that the formed Mo₂NiB₂ particles at lower temperatures could be as seeds for the further formation of Mo₂NiB₂ directly from the raw materials of Mo, Ni and B at higher temperatures. The appearance of liquid phases between 1100 and 1200 °C was important for the densification of hard alloy. The microstructures of the hard alloys were observed by SEM. The main fracture modes for the hard alloys were different for the samples sintered at different temperatures. The maximum bending strength and the Rockwell hardness reached 1.85 ± 0.04 GPa and 85.7 ± 0.1 HRA, respectively. These values were comparable to those reported in literature.