Atomic-scale study on the precipitation behavior of an Al-Zn-Mg-Cu alloy during isochronal aging  

作　　者：Xingpu Zhang Xiaotong Deng Haofei Zhou Jiangwei Wang 

机构地区：[1]Center of Electron Microscopy and State Key Laboratory of Silicon Materials,School of Materials Science and Engineering,Zhejiang University,Hangzhou 310027,China [2]Center for X-Mechanics,Department of Engineering Mechanics,Zhejiang University,Hangzhou 310027,China [3]Wenzhou Key Laboratory of Novel Optoelectronic and Nano Materials,Institute of Wenzhou,Zhejiang University,Wenzhou 325006,China

出　　处：《Journal of Materials Science & Technology》2022年第13期281-292,共12页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.52071284 and 51771172)。

摘　　要：The precipitation behavior of a 7075 Al alloy during isochronal heat treatments at three different heating rates has been studied using differential scanning calorimetry,high-angle-annular-dark-field scanningtransmission-electron microscope and density functional theory calculation.In the early stage of aging,GPI and GPII zones form sequentially and cause two characteristic DSC peaks.Subsequently,the formation ofη_(1) precipitates takes place concurrently withη’.A novel type of metastable phaseη_(1)’is identified as the precursor ofη_(1),which can lower the lattice misfit betweenη_(1) and Al matrix along the direction of[1010]_(η_(1))//[001]_(Al).Accordingly,a pathway for the formation ofη_(1) viaη_(1)’is demonstrated.Precipitatesη’together withη_(1) andη_(1)’contribute to the third DSC peak.With the further increase of temperature,ηprecipitates become prevailing.Based on the quantitative analyses,the influence of the heating rate and ending temperature on the cross section and number density of phases formed is discussed.

关 键 词：Al-Zn-Mg-Cu alloys PRECIPITATION Isochronal ageing HAADF-STEM Density functional theory 

分 类 号：TG146.21[一般工业技术—材料科学与工程]