First-principles study of high-pressure structural stability and mechanical properties of Ni2B

Abstract The structural stability and mechanical properties of Ni2B with I4/mcm space group under various external pressure are indagated utilizing the first-principle calculations. The calculated phonon dispersion curves, formation enthalpy and elastic constants clarify that I4/mcm phase has dynamical, thermodynamic and elastic stability. The theoretical elastic modulus by stress–strain method shows that the I4/mcm structure has a small anisotropy. The intrinsic mechanism affecting the mechanical properties of Ni2B structure is confirmed according to the calculated the ideal strength values under a series of strains and the two-dimensional electron localization function plots corresponding to the key several structural models. The comprehensive results manifest that the structural failure of Ni2B with I4/mcm symmetry mainly stems from the break of Ni-B covalent bond along the specific shear strain direction.