First-principles calculations of structural, elastic and electronic properties of AB2 type intermetallics in Mg–Zn–Ca–Cu alloy

Electronic structure and elastic properties of MgCu2, Mg2Ca and MgZn2 phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory (DFT). The calculated lattice parameters were in good agreement with the experimental and literature values. The calculated heats of formation and cohesive energies shown that MgCu2 has the strongest alloying ability and structural stability. The elastic constants of MgCu2, Mg2Ca and MgZn2 phases were calculated, the bulk moduli, shear moduli, Young's moduli and Poisson's ratio were derived. The calculated results shown that MgCu2, Mg2Ca and MgZn2 are all ductile phases. Among the three phases, MgCu2 has the strongest stiffness and the plasticity of MgZn2 phase is the best. The density of states (DOS), Mulliken electron occupation number and charge density difference of MgCu2, Mg2Ca and MgZn2 phases were discussed to analyze the mechanism of structural stability and mechanical properties.