Mechanical properties and electronic structures of MgCu2, Mg2Ca and MgZn2 Laves phases by first principles calculations

Mechanical properties and electronic structure 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 are in good agreement with the experimental and literature values. The calculated heat of formation and cohesive energies showed that MgCu2 has the strongest alloying ability and structural stability. Elastic constants of MgCu2, Mg2Ca and MgZn2 were calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio were derived. The calculated results show 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. Melting points of the three phases were predicted using cohesive energy and elastic constants. Density of states (DOS), Mulliken population, electron occupation number and charge density difference were discussed. Finally, Debye temperature was calculated and discussed.