Atomic-scale roles of Zn element in age-hardened AlMgSiZn alloys

N.N.Jiao¹，Y.X.Lai¹，S.L.Chen²，P.Gaob²，J.H.Chen¹

1. Center for High-Resolution Electron Microscopy,College of Materials Science & Engineering,Hunan University2. Electron Microscopy Laboratory and International Center for Quantum Materials,School of Physics,Peking University

摘 要：Adding alloying elements to improve the performances or the manufacturing processes of Al-Mg-Si alloys has long been a serious issue in developing advanced automotive aluminum materials. The Zn element,among those promising ones, has demonstrated positive alloying effects on Al-Mg-Si alloys. However,the atomic-scale roles of Zn in an age-hardened Al-Mg-Si-Zn alloy have not been adequately understood.Using atomic-resolution electron microscopy, here we report the precise locations of Zn elements in all hardening precipitates involved and their alloying mechanism at the atomic scale when alloying the alloy. Our results show that Zn atoms enter all the major hardening phases to occupy specific featured atomic sites of the original elements, e.g. the Si1 and Mg2 sites in the β’-2 phase, and modify their crystal structures, interfacial structures and morphologies in characteristic manners. It is revealed that for the β’-phase, Zn atoms occupy unique atomic sites, whereas for other phases, they demonstrate similar behaviors as other additive alloying elements such as Ag and Cu do.

关键词：