Mg-Al-Ca合金中三元Laves相的稳定性和电子结构

采用基于密度泛函理论的第一性原理方法，应用VASP (Vienna Ab-initio Simulation Package) 计算软件，研究了Mg-Al-Ca合金中三元Laves相，即Ca(Mg1-x,Alx)2和Al2(Ca1-x,Mgx) (x=0, 0.25, 0.50, 0.75, 1)在不同形态结构(C14, C15和C36)下的相稳定性及电子结构。计算所得的晶格常数和实验值吻合很好，形成能和相关能的计算用来研究三元Laves相的合金化能力和稳定性，结果表明：C14-Ca(Mg0.25,Al0.75)2具有很好的合金化能力,而C15- CaAl2具有很好的结构稳定性。态密度和电荷密度的计算用来研究Mg-Al-Ca合金中三元Laves相稳定性的内在微观机制。

Stability and electronic structure of ternary Laves phase in Mg-Al-Ca alloys

We have carried out the first-principles theoretical calculations based on density-functional theory to investigate the phase stability and electronic structure of Ca(Mg1-x,Alx)2 and Al2(Ca1-x,Mgx) (x=0, 0.25, 0.50, 0.75, 1) with C14-, C15- and C36- structures in Mg-Al-Ca ternary Laves phases . The obtained lattice constants are in good agreement with the experimental values. The heat of formation and cohesive energy are calculated and used to study the stability of Ca(Mg1-x,Alx)2 and Al2(Ca1-x,Mgx) Laves phases. The results show that C14-Ca(Mg0. 25,Al0.75) has the strongest alloying ability and C15-CaAl2 has the best stability of all the investigated Laves phases in Mg-Al-Ca alloy. The density of states (DOS) and charge density distribution are used to study the underlying mechanism of structure and phase stability of ternary Laves phases in Mg-Al-Ca alloys.