基于第一性原理的AlP/Mg2Si异质形核界面建模方法

Modeling Method of AlP/Mg2Si Heterogeneous Nucleation Interface based on First-principles

Mg2Si作为第二相在过共晶Al/Mg2Si合金中起到颗粒增强的作用,使该复合材料具有优良的综合性能。但作为初生相的Mg2Si极易生长成枝晶状,严重降低铝合金的性能。通过添加P元素细化变质处理可以有效改善初生Mg2Si的形貌及尺寸,并且通过错配度理论可知AlP可作为初生Mg2Si的形核衬底。但若仅依赖于晶格错配度理论和试验现象,无法揭示细化机理的本质,因此,近些年第一性原理方法逐渐在异质形核细化晶粒机制研究方面得到应用。本文选取错配度为1.10%的AlP(331)/Mg2Si(110)异质形核界面进行建模过程介绍,为后续对异质形核界面的电子结构及界面结合能的计算做准备,并得出用第一性原理研究异质形核界面时构建模型的一般方法。

As the second phase,Mg2Si plays a role in particle reinforcement in hypereutectic aluminum alloy,which makes Al/Mg2Si composites have good comprehensive properties.However,as the primary phase,Mg2Si is easy to grow into dendrite,which seriously reduces the properties of aluminum alloy.The morphology and size of primary Mg2Si can be improved by P element refinement modification,and AlP can be used as nucleation substrate of primary Mg2Si through mismatch theory.However,if it only depends on the lattice mismatch theory and experimental phenomena,it cannot reveal the essence of refinement mechanism.Therefore,in recent years,the first principle method has been gradually applied in the study of heterogeneous nucleation and grain refinement mechanism.In this paper,the modeling process of AlP(331)/Mg2Si(110)heterogeneous nucleation interface with 1.10%mismatch is introduced,which prepares for the calculation of the electronic structure and interface binding energy of the heterogeneous nucleation interface.And the general method of constructing the model when using the first principle to study the heterogeneous nucleation interface is introduced in this paper.