Stabilizing a severely deformed Al-7Mg alloy with a multimodal grain structure via Mg solute segregation  

作　　者：Min Zha Hong-Min Zhang Xiang-Tao Meng Hai-Long Jia Shen-Bao Jin Gang Sha Hui-Yuan Wang Yan-Jun Li Hans J.Roven 

机构地区：[1]State Key Laboratory of Superhard Materials,Jilin University,Changchun,130012,China [2]Key Laboratory of Automobile Materials of Ministry of Education&School of Materials Science and Engineering,Nanling Campus,Jilin University,Changchun,130025,China [3]International Center of Future Science,Jilin University,Changchun,130012,China [4]Department of Materials Science and Engineering,Norwegian University of Science and Technology,7491,Trondheim,Norway [5]Department of Materials Science and Engineering,Nanjing University of Science and Technology,Nanjing,210094,China

出　　处：《Journal of Materials Science & Technology》2021年第30期141-149,共9页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51922048,51790483 and 51871108);the Changjiang Scholars Program(No.T2017035)。

摘　　要：Single-phase Al-Mg alloys processed by severe plastic deformation(SPD)usually suffer from unsatisfactory thermal stability at moderate to high temperatures with recrystallization occurring and obvious grain coarsening.In the present work,an Al-7Mg alloy prepared by equal-channel angular pressing(ECAP)possessed markedly enhanced thermal stability upon annealing at moderate to high temperatures(200-275℃),compared with those ultrafine-grained dilute Al-Mg alloys with a uniform microstructure.The enhanced thermal stability is due primarily to the multimodal grain structure consisting of nano-,ultrafine-and micron-sized grains,strong segregation and/or clusters of Mg solute along grain boundaries(GBs),and Al_(3)Mg_(2)precipitates formed during annealing.First,extensive recovery predominates over recrystallization and consumes most of the stored energy in the ECAPed Al-7Mg alloy annealed at≤275℃,leading to the recrystallization and growth of nano/ultrafine grains being retarded or postponed.Moreover,Mg solute segregation and/or clusters along GBs of nano/ultrafine grains could further suppress grain growth via diminishing GB energy and dragging GBs efficiently.In addition,Al_(3)Mg_(2)precipitates formed with increasing annealing time could inhibit grain growth by pinning GBs.The present multimodal-grained Al-7Mg alloy with enhanced thermal stability is believed to be particularly attractive in potential engineering applications at moderate to high temperatures.

关 键 词：Al-Mg alloys ECAP Multimodal grain structure Solute segregation Thermal stability 

分 类 号：TG146.21[一般工业技术—材料科学与工程]