Structural, elastic and electronic properties of Mg(Cu1−xZnx)2 alloys calculated by first-principles

The structural, elastic and electronic properties of Mg(Cu1−xZnx)2 alloys (x = 0, 0.25, 0.5,and 0.75) were investigated by means of first-principle calculations within the framework of density functional theory (DFT). The calculation results demonstrated that the partial substitution of Cu with Zn in MgCu2 leaded to an increase of lattice constants, and the optimized structural parameters were in very good agreement with the available experimental values. From energetic point of view, it was found that with increase of Zn content the structural stability of Mg(Cu1−xZnx)2 alloys decreased apparently. The single-crystal elastic constants were obtained by computing total energy as a function of strain, and then the bulk modulus B, shear modulus G, Young's modulus Y and Poisson's ratio ν of polycrystalline aggregates were derived. The calculated results showed that among the Mg(Cu1−xZnx)2 alloys, MgCuZn exhibited the largest stiffness, while Mg2Cu3Zn showed the best ductility. Finally, the electronic density of states (DOSs) and charge density distribution were further studied and discussed.

Research highlights▶ The optimized lattice parameter and volume increased with Zn content while structural stability became weaker. ▶ Mg2Cu3Zn showed the best ductility while MgCuZn exhibited the largest stiffness but obvious brittleness. ▶ The covalent bond became weak with Zn content. ▶ The elastic constant corresponding to not volume conserving was higher due to the influence of electrostatic interaction energy.