Mg合金晶粒细化机理的电子理论研究

采用递归法计算了α-Mg与α-Zr的结构能、原子结合能，Mg/Zr界面能与Mg/液态Mg界面能，Mg中Zr及Zr中Fe，Mn，Si等杂质原子相互作用能.计算发现α-Zr的结构能、原子结合能低于相应的α-Mg，且Mg/Zr界面能低于Mg/液态Mg界面能，从能量角度合理解释了Zr先于Mg从Mg熔体析出，并作为异质核心细化Mg晶粒的实验现象.原子相互作用能的计算结果显示，Zr在Mg中相互吸引形成团簇，并与杂质形成化合物，削弱晶粒细化效果. 关键词： 电子结构 晶粒细化 Mg合金

Electron-theoretical study of grain refining mechanism of Mg alloys

The electronic parameters，such as the structural energy and atom binding energy of both α-Mg and α-Zr，the Mg/Zr interface energy and surface energy of Mg，as well as the interaction energies between Zr atoms and between Zr and impurity atoms，were calculated by means of recursion method. The calculated results showed that the structural energy and atom binding energy of α-Zr are lower than those of α-Mg，and the Mg/Zr interface energy is lower than the surface energy of Mg，which，in an energetical point，explains the experimental phenomenon. Specifically，Zr particles first crystallize out of the Mg liquid and then act as heterogeneous nucleation sites to refine the Mg grains. The atom interaction energies indicate that the Zr atoms can attract each other to form Zr atom clusters in Mg，and combine with impurity atoms to form compounds，thus weakening the Mg grain refining effect.