中文摘要：

采用基于密度泛函理论（DFT）的第一性原理超软赝势平面波方法，研究了Al、Zn对Mg-Li合金中α-Mg／β-Li相界断裂强度的影响。体系结合能的计算结果表明Al、Zn固溶于Mg-Li合金后其结构更为稳定；从所得断裂功、态密度以及电荷密度的结果来看，Al更容易固溶于α-Mg固溶体中，对断裂强度的增强作用优于占位于α-Mg／β-Li相界面；Zn占位于α,β晶内、相界面的倾向性不明显，但均可使体系的断裂强度提高；Al、Zn复合合金化后使体系稳定性得到提高，断裂强度等得到进一步的改善。环境敏感镶嵌能的计算结果表明Zn比Al更容易偏聚于相界面；Al、Zn合金化对体系稳定性、断裂强度产生的影响主要是由于Al-3s3p轨道电子、Zn3d轨道电子贡献产生了新的成键峰，以及Mg2p轨道及Li2s轨道电子在费米能级处共同作用的结果。

英文摘要：

According to the first principle ultrasoft pseudopotential plane wave method based on the density functional theory （DFT）, the effect of Al and Zn doping on the rupture strength of Mg-Li phase interface was investigated. The cohesive energy calculation shows that the structure of Mg-Li alloy with AI and Zn solid solution is more stable. The calculation of density of states, charge density and work of rupture suggests that Al is more easily dissolved into a-Mg phase, and its enhancement to the rupture strength is superior to that of a-Mg/fl-Li phase interface. Zn can improve rupture strength dissolving in grain and phase interface. Al and Zn addition can further improve the stability of the system and rupture strength. The calculation of environment-sensitive embedding energy shows that Zn segregates to the phase interface more easily than Al. The Al and Zn alloying effect on the structure stability and rupture strength in mainly contributed by 3p and 3s states of Al, the new peak of 3d states of Zn and the hybridization between Mg-2p and Li-2s at the Fermi level.