First Principles Calculations Of Mg-Zn Magnesium Alloys

In recent years, the calculation method in various fields of natural science has been greatly developed, including condensed matter physics, materials science, computer science,and chemistry. First-principles calculation method has become a commonly used means of scientific research, is closely linked with theory and experiment. First-principles calculation method, which based on density functional theory(DFT), are used to calculate the the energy and property of Mg-Zn-Cu intermetallic compounds in magnesium alloy in this paper, which can provide theoretical guidance for the development of Mg-Zn-Cu alloy.Structural stability, electronic structure, elastic properties and Debye temperature of MgCu2, MgZn2 and CuZn phases were investigated by means of Materials Studio from CASTEP program based on density functional theory(DFT). The calculated heats of formation and cohesive energies show that among the three metallic compound, MgCu2 has the strongest alloying ability and structural stability. By using the calculation results of density of states, Mulliken electron occupation number and metallicity analysis, and further confirem the mechanism about structural stability of the three phases. The calculated mechanical properties of MgCu2, MgZn2 and CuZn(elastic properties, bulk modulus, shear modulus,Young’s modulus, Poisson’s ratio) show that CuZn phase has the strongest ability to resist deformation and shear strain deformation, and it also has the strongest stiffness and hardness.The Debye temperature can be deduced from elastic constants, and CuZn is highest.This paper further calculate structural stability, mechanical properties, hardness,electronic structure, Debye temperature, heats of formation, cohesive energies, elastic constants, elasticity modulus, Poisson’s ratio and Cauchy pressure of MgCu2 and MgZn2 under a function of pressures ranging from 0 to 80 GPa. It also calculated elastic anisotropic parameters under various pressures of MgZn2. The calculated results showed that the bulk modulus B, shear modulus G, Young’s modulus E, Poisson’s ratio ν and Cauchy pressure of MgCu2 and MgZn2 rise,while the anisotropy of MgZn2 a bit decrease with the increase of pressure. MgCu2 and MgZn2 phase were ductile phases according to that they perform better with the increase of pressure and pressure does not change G/B under a function of pressures ranging from 0 to 80 GPa. In addition, the electronic densities of states(DOS) of MgCu2 andMgZn2 under a function of pressures were analyzed. With the change of pressure, the electronic composition participating in hybridization has also changed.