[T15] Hard Materials

[17F-T15-10] Substitution Effects on the Crystal Structure and Nano-Micro Hardness of the Mo₂NiB₂-Ni Cermets

*S. Maruyama¹, S. Ichijo¹, Y. Harada¹, E. Takahashi¹, T. Hirano¹, R. Maki² (1.Tokyo City University, Japan, 2.Okayama University of Science, Japan)

Keywords:boride, cermet

Mo₂NiB₂-Ni cermets have been investigated through the substitution of transition metals to metal-site of the Mo₂NiB₂ phase, aiming to improve its mechanical properties. By substituting Cr and V to the Mo₂NiB₂, the crystal structure of the Mo₂NiB₂ phase is changed from an orthorhombic-type structure to a tetragonal-type structure, and mechanical properties show enhancement. However, the relationship between crystal structure deformation and mechanical properties is unknown. In this study, we investigated the nano-submicron hardness of the Cr, V substituted Mo₂NiB₂-Ni cermet using nano-indentation. In addition, we also performed the first principal calculation to evaluate the chemical bonding in the Mo₂NiB₂ phase.The relationships between the hardness of the boride phase and the crystal structure deformation on the mechanical properties will be presented.