金属化合物MgAg和MgY在压力下力学性能的第一性原理计算

First Principles Calculation of Mechanical Properties of Metal Compounds Mg Ag and Mg Y Under Pressure

采用基于密度泛函理论(DFT)的第一性原理计算,计算了镁合金中金属化合物Mg Ag和Mg Y在0~20 GPa压力下力学性能。计算在0 GPa压力下Mg Ag和Mg Y的晶胞参数、体模量、剪切模量、杨氏模量、泊松比等数据。结果表明:Mg Ag和Mg Y均满足力学性质稳定性,Mg Ag的抗剪切能力、抵抗变形能力、刚度、延展性均比Mg Y强;而Mg Y塑性好于Mg Ag。在0~20 GPa压力作用下Mg Ag和Mg Y的晶胞晶格常数和晶胞体积均随压力增加而变小,并且Mg Y比Mg Ag的变形率更大,二者的抗变形能力和抗剪切能力均有所增加;Mg Ag和Mg Y的脆性在减弱,延展性在逐渐增加,二者塑性均随着压力增加而增加,二者的结合力均表现为中心原子力,各向异性也均随压力增加而增加。

The mechanical properties of MgAg and MgY phase were calculated by the first-principles method under different pressures from 0 to 20 GPa. The adopted first-principles were based on density functional theory （DFT） with the generalized gradient approximation. The calculation result of the lattice parameters, bulk modulus, shear modulus, Young＇s modulus and Poisson＇s ratio of MgAg and MgY at 0 GPa shows that both MgAg and MgY satisfy the stability of mechanical properties. The shear resistance, deformation resistance, rigidity and ductility of MgAg are higher than MgY, while the plasticity of MgY is higher than MgAg at 0 GPa. Calculation result of mechanical properties of MgAg and MgY under 0-20 GPa shows that with the pressure increasing, the lattice parameters and cell volume both decrease gradually （the deformation rate of MgY is higher）, the ability of resisting both deformation and shear capacities increases, the brittleness of MgAg and MgY decreases gradually, the ductile behavior increases, the elastic anisotropy increases, and the binding force of the central atomic force as well as anisotropy increase.