Anomalous crystal structure of γ' phase in the Mg-RE-Zn(Ag) series alloys:Causality clarified by ab initio study

查看全文 作　　者：Junyuan [1]Bai;Xueyong [1,2]Pang;Xiangying [1]Meng;Hongbo [1]Xie;Hucheng [1,2]Pan;Yuping [1,2]Ren;Min [1,2]Jiang;Gaowu [1,2]Qin

机构地区：[1]Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education),School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China;[2]Research Center for Metallic Wires,Northeastern University,Shenyang 110819,China

出　　处：《Journal of Materials Science & Technology》索引2020年第36卷第1期,共9页

基　　金：supported by the National Key Research and Development Program of China(No.2016YFB0701202);the Fundamental Research Funds for the Central Universities(No.N160208001);the National Natural Science Foundation of China(Nos.51525101,51501032,and U1610253)。 摘　　要：The crystal structure of the single-unit-cell thickness γ ' phase,as a key strengthening phase in Mg-REZn(Ag) series alloys,has been extensively studied,and several structural models have been proposed in the past two decades.However,these reported models,and even the lattice constants at the same proposed structure,are scattered severely,which has led to considerable confusion and not available for further mechanical property simulation and prediction of Mg alloys containing this phase.In this study,by using first-principles calculations,the crystal structure of y' phase is clarified,resolving the discrepancies among different experiments,and its intrinsic mechanical properties have also been studied for the first time.It is verified that the γ ' phase contains quasi-five atomic layers,instead of the previously reported tri-layer,and surprisingly,its crystal structure has many variants,which would change with the alloy composition.Besides,with the help of the simulated selected area electron diffraction(SAED) patterns,it is found that the atoms in the central layer remain partially ordered distribution,and this ordered extent primarily depends on the atomic ratio of RE:Zn(Ag) and the solute content in an alloy.That is,the ordered extent increases with decreasing the atomic ratio of RE:Zn(Ag) and/or increasing solute content of alloy,and vice versa.Ag and Zn dissolved in the γ' phase would produce almost opposed mechanical anisotropy for the γ ' phase under the identical crystal structure,and the addition of Ag shows more efficient on increasing the shear modulus of γ' phase. 关键词：FIRST-PRINCIPLES γ'phase Mg-RE-based SERIES ALLOYS Crystal structure Mechanical-properties

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Anomalous crystal structure of γ' phase in the Mg-RE-Zn(Ag) series alloys:Causality clarified by ab initio study

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