Comprehensive investigation on the structural,electronic and mechanical properties of T-Mg_(32)(Al,Zn)_(49)phases in Al-Mg-Zn alloys  

作　　者：Boyu Xue Wei Xiao Xiwu Li Guanjun Gao Xiaowu Li Yongan Zhang Ligen Wang Baiqing Xiong 

机构地区：[1]State Key Laboratory of Nonferrous Metals and Processes,China GRINM Group Co.,Ltd.,Beijing 100088,China [2]GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China [3]General Research Institute for Nonferrous Metals,Beijing 100088,China [4]Department of Materials Physics and Chemistry,School of Materials Science and Engineering,Key Laboratory for Anisotropy and Texture of Materials,Ministry of Education,Northeastern University,Shenyang 110819,China

出　　处：《Journal of Materials Science & Technology》2024年第6期237-246,共10页材料科学技术（英文版）

基　　金：financially supported by the National Key R&D Program of China(No.2020YFF0218200);the Innovation Fund Project of GRINM,and other related projects.

摘　　要：In the development process of crossover aluminum alloys,T-Mg_(32)(Al,Zn)_(49)phases play a significant role in the precipitation strengthening effect.However,comprehensive understandings of the structural characteristics,interactions among alloying elements,mechanical property dependence on composition variation,effects of doping and defects etc.are still inadequate.A combination of density functional theory(DFT)calculations and special quasi-random structures(SQSs)was applied to investigate the formation energies,lattice parameters,electronic structures and mechanical properties of the disordered T-phases,as well as the effects of possible defects and alloying elements.The formation energy and lattice constant of the T-phase gradually vary from 0 to-0.12 eV/atom and from 1.460 to 1.405 nm,respectively,with increasing Zn contents.Zn-3d orbitals exhibit stronger hybridization with Al-3s than Mg-3s orbitals,and this is further enhanced by increasing Zn contents,leading to improved covalency and mechanical properties of the T-phase.The T-phases show good ductility according to the Poisson's ratio ν,Cauchy's pressure and G/B.The A site is more favorable to remain vacant in Al-rich and Zn-poor environments,which is consistent with the previous experimental observations.For alloying elements,Zn atoms tends to occupy Al atoms at the B,C and F sites and Mg atoms at the G sites.Both Cu and Ag elements can decrease the formation energy of T-phases and possibly produce a greater number of T-phases during the precipitation process.The effect of Ag is more significant relative to Cu due to the deeper orbital hybridization.The computational results show good agreement with previous experimental data and provide new insights into the compositional design of new Al-Mg-Zn alloys.

关 键 词：Al-Mg-Zn alloys PRECIPITATION Mechanical properties Thermodynamic stability Density functional theory 

分 类 号：TG146.21[一般工业技术—材料科学与工程]