Study of Mo3NiB3 and Mo2NiB2 cermets by first-principles calculation and experiment

Abstract

In this work, the mechanical properties of Mo₃NiB₃ and Mo₂NiB₂ phases in Mo-Ni-B cermets were studied. The first-principles calculation results demonstrate the thermodynamic and mechanical stability of both Mo₃NiB₃ and Mo₂NiB₂. Among them, Mo₂NiB₂ shows superior stability and toughness compared to Mo₃NiB₃. On the other hand, the Young’s modulus and hardness values of Mo₃NiB₃ are higher than those of Mo₂NiB₂. Mo₃NiB₃ exhibits enhanced isotropy and stronger covalent bonding properties, as confirmed by DOS and Mulliken analysis. Further research shows that Mo₃NiB₃ has brittleness (B/G = 1.586) and high Vickers hardness (22.3 GPa), indicating its potential use as a wear-resistant material. To validate the accuracy of the theoretical calculations, Mo₃NiB₃ and Mo₂NiB₂ cermets were fabricated through vacuum hot pressing sintering, followed by comprehensive analysis of their microstructure and mechanical properties. Specifically, the experimentally measured compressive strength and hardness values of Mo₃NiB₃ (3213.2 MPa and 3264.2 HV0.3, respectively) were closely matched by the theoretical predictions. Notably, these experimental findings are in good agreement with the theoretically calculated values. This investigation provides reference value for a more in-depth analysis of the mechanical properties of Mo-Ni-B cermets, provides a theoretical and practical basis for its application in the field of materials, and promotes the development of Mo-Ni-B cermets materials.