Nano-micro Hardness of the Mo<sub>2</sub>NiB<sub>2</sub>-Ni Cermets

Mo2NiB2-Ni cermets, one of the boride-base cermet, have been investigated as an alternative material to WC cemented carbides. By adding Cr and V to the Mo2NiB2-Ni cermet, the crystal structure of the Mo2NiB2 is changed from orthorhombic type to tetragonal type, and mechanical properties show enhancement. However, details of structure deformation and the mechanical properties of Mo2NiB2 phases still need to be discovered. In this study, we performed a nano indentation measurement to investigate the hardness of the Mo2NiB2 phases. Cr and V doped complex boride base cermets with tetragonal structure-type and non-doped Mo2NiB2-Ni cermet with orthorhombic type structure were sintered using Reaction Boronising Sintering method proposed K. Takagi. According to the nano-indentation measurement, the hardness of the tetragonal phase exhibited 25 - 28 GPa, while that of the orthorhombic phase showed 20 - 23 GPa.