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 Mg2 X 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), Mg63 X32 Bi, Mg64 X31 Bi, Mg64 Ge32 Bi, and Mg64 Sn32 Bi are mechanically stable, while Mg64 Si32 Bi 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 Mg63 X32 Bi, Mg64 X31 Bi, and Mg63 X32 Bi are different, resulting in different hybridization effects in three types of Bi-doped Mg2X.