Y掺杂MgZn_(2)稳定性、电子结构和力学性能的第一性原理计算  

First-principles Calculations of Stability,Electronic Structure and Mechanical Properties of Y-doped MgZn_(2)

作　　者：陈敬昶 刘建国 陆绍敏 钟丽辉[1] 陈丽萍 王远[1] CHEN Jing-chang;LIU Jian-guo;LU Shao-min;ZHONG Li-hui;CHEN Li-ping;WANG Yuan(Southwest Forestry University,Kunming 650224,China;YYCIN No.7 Construction Co.,Ltd.,Kunming 650100,China)

机构地区：[1]西南林业大学,昆明650224 [2]云南建投第七建设有限公司,昆明650100

出　　处：《表面技术》2023年第8期444-450,共7页Surface Technology

基　　金：国家自然科学基金(51301144);云南省教育厅科学研究基金(2022Y574)。

摘　　要：目的稀土元素Y掺杂是改善7xxx系铝合金断裂韧性的重要途径,然而因其掺杂量极低,通过实验很难测定微量Y对7xxx系铝合金析出相及强韧机制产生的作用,限制了7xxx系铝合金的进一步发展。采用第一性原理计算方法探究Y掺杂对7xxx系铝合金中重要析出相MgZn_(2)的影响机理,为7xxx系铝合金的微合金化强韧机理研究提供理论依据。方法构建适于第一性原理计算、Mg/Zn的原子数分数比为1∶2的晶体模型,Y原子通过替换Mg或Zn原子的方式进行掺杂,通过能量计算、电子计算和弹性常数计算等分析Y掺杂对MgZn_(2)能量稳定性、电子结构和力学性能的影响机理。结果经Y掺杂后,形成3种固溶体Mg_(3)Zn_(8)Y、Mg_(4)Zn_(7)Y-1和Mg_(4)Zn_(7)Y-2,它们的形成热均小于0,即它们均可自发形成且稳定存在。通过结合能计算发现,3种固溶体的结合能都小于MgZn_(2)的结合能,说明Y掺杂促进了MgZn_(2)的稳定性。通过电子结构分析发现,Y掺杂后与Mg、Zn原子形成强的共价键,增强了体系的稳定性,Mg-Zn原子间形成了强离子键,MgZn_(2)中Zn-Zn原子间的共价键变为强离子键。力学性能计算结果表明,经Y掺杂后MgZn_(2)的硬度降低、韧性上升,即Y掺杂增强了7xxx系铝合金中重要弥散析出相MgZn_(2)的韧性,从而提升了7xxx系铝合金的断裂韧性和抗疲劳能力。结论基于计算结果分析得出,Y掺杂提升了MgZn_(2)的稳定性、键合强度和断裂韧性,相关计算分析为微量Y掺杂增强7xxx系铝合金断裂韧性的实验分析提供了指导。Micro-alloying of rare earth element Y is an important way to strengthen the fracture toughness of 7xxx series aluminum alloys,but it is hard to determine the effect of Y doping on the precipitated phase and toughness mechanism of 7xxx series aluminum alloys in experiments because the doping amount of Y is very small,which limits the further development of 7xxx series aluminum alloys.Therefore,the influence mechanism of Y doping on the important precipitation phase MgZn_(2)in 7xxx series aluminum alloys was analyzed by the first principles calculation method in this paper,in order to provide a theoretical basis for study of the strengthening and toughening mechanism of 7xxx series aluminum alloys by micro-alloying elements.A crystal model with the atomic ratio of Mg/Zn=1∶2,which was suitable for first-principles calculation,was built in this paper,then Mg or Zn atoms were replaced with Y atoms by orderly substitution doping and the influence mechanism of Y doping on the energy stability,electronic structure and mechanical properties of MgZn_(2)was analyzed by energy calculations,electronic calculations and elastic constant calculations.The results showed that after Y doping,the formation heat of Mg_(3)Zn_(8)Y,Mg_(4)Zn_(7)Y-1 and Mg_(4)Zn_(7)Y-2 was−19.998,−7.14 and−3.916 kJ/mol respectively,so the three solid solutions could spontaneously form and exist stably.It could be found that the structural stability of MgZn_(2)could be enhanced by Y doping,and the formed solid solution Mg_(3)Zn_(8)Y with Y substituting for Mg had the most stable structure and the formed solid solution Mg_(4)Zn_(7)Y-2 with Y substituting for had the worst stability,since the binding energy of MgZn_(2),Mg_(3)Zn_(8)Y,Mg_(4)Zn_(7)Y-1 and Mg_(4)Zn_(7)Y-2 were−132.664,−163.584,−153.648 and−150.424 kJ/mol,respectively,obtained from the computation of binding energy.The solid solution Mg_(4)Zn_(7)Y-2 hardly formed with Y doping due to their poor formation ability and structural stability,so the electronic structure and mechanical

关 键 词：MgZn_(2) Y掺杂 电子结构 力学性能 第一性原理计算 

分 类 号：TG135[一般工业技术—材料科学与工程]