Investigation on Influence of Cr on the Mechanical Properties of Mo_2NiB_2 by the First-Principles Calculation

摘要

The first-principles using the pseudopotential plane-waves and based on density functional theory, within the generalized gradient approximation (GGA) for the exchange and correlation potential, was applied to study the formation energy, lattice parameters, elastic constants, modulus, Poisson's ratio, bulk-to-shear modulus ratio, and elastic anisotropy of pure and Cr doped Mo_2NiB_2. The calculated lattice parameters, Young's modulus and hardness were compared availably with other experimental and theoretic values. The Cr doping influence the orthogonal and tetragonal structural Mo_2NiB_2 compounds, and the Cr doped tetragonal structure Mo_2NiB_2 has the best mechanical properties for hard alloy. According to the electronic structure of these compounds, the nonmetal-metal hybridization and metal-metal interactions lead to the relatively high hardness and toughness, respectively.