First Principle Study on Mg2X (X = Si, Ge, Sn) Intermetallics by Bi Micro-Alloying

Abstract

Being a positive candidate reinforcement material for laminar composites, the Mg2X (X = Si, Ge, Sn) based intermetallics have attracted much attention. The elastic properties, anisotropy, and electronic properties of intermetallic compounds with Bi-doped Mg2X (X = Si, Ge, Sn) are calculated by the first principles method. Results show that the lattice parameters of Mg2X are smaller than those of Bi-doped Mg2X. The element Bi preferentially occupies the position of the X (X = Si, Ge, Sn) atom than other positions. Mg2X (X = Si, Ge, Sn), Mg63X32Bi, Mg64X31Bi, Mg64Ge32Bi, and Mg64Sn32Bi are mechanically stable, while Mg64Si32Bi indicates that it cannot exist stably. The doping of alloying element Bi reduces the shear deformation resistance of the Mg2X (X = Si, Ge, Sn) alloy. The pure and Bi-doped Mg2X (X = Si, Ge, Sn) exhibits elastic and anisotropic characteristics. The contribution of the Bi orbitals of Mg63X32Bi, Mg64X31Bi, and Mg63X32Bi are different, resulting in different hybridization effects in three types of Bi-doped Mg2X.