First-principles calculations on the structural stability and elastic constant of Mg8Sn4-xMx
Using the CASTEP software based on density functional theory,the crystal structure model of Mg8Sn4-xMx(M=Al,Cu;x=0,1 or 2)was constructed,and its lattice constant,structural stability and elastic constant were calculated by first-principles,as well as the electronic properties,elastic properties and intrinsic hardness of the crystal structure model with different amounts M atoms solid solution in Mg2Sn phase were ana-lyzed.The calculation results show that the solid solution of the M atoms in Mg2Sn can generate spontaneously,and the obtained Mg8Sn4-xMx(x=1 or 2)crystal structure can exist stably;the crystal structure converts from cubic system to tetragonal system when two M atoms dissolve in Mg2Sn.The analysis results of density of states indicate that the atoms in the system exist obvious orbital hybridization by M atoms solid solution,then show strong covalent bonds,and increasing the number of M atoms will not affect the contribution of each atom to the density of states,but will increase the contribution of electrons in the atom to the density of states.The analysis results of elastic properties and intrinsic hardness indicate that the mechanical properties of the system are still stable after dissolving M atoms in Mg2Sn,and the hardness of the system decreases gradually and the plasticity increases continuously with the increase of M atoms solid solubility,i.e.,the toughness and plasticity of the sys-tem can be improved by increasing M atoms solid solubility.
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