Microstructure evolution and dislocation configurations in nanostructured Al-Mg alloys processed by high pressure torsion

作     者：刘满平 蒋婷慧 谢学锋 刘强 李雪峰 Hans J.ROVEN Man-ping LIU;Ting-hui JIANG;Xue-feng XIE;Qiang LIU;Xue-feng LI;Hans J ROVEN

作者机构：材料科学与工程学院江苏省材料摩擦学重点实验室镇江212013 Department of Materials Science and Engineering Norwegian University of Science and Technology Center for Advanced Materials Qatar University 

出 版 物：《Transactions of Nonferrous Metals Society of China》 (中国有色金属学报（英文版）)

年 卷 期：2014年第24卷第12期

页      面：3848-3857页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 08[工学] 080501[工学-材料物理与化学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：Project(BK2012715)supported by the Basic Research Program(Natural Science Foundation)of Jiangsu Province,China Project(14KJA430002)supported by the Key University Science Research Project of Jiangsu Province,China Project(50971087)supported by the National Natural Science Foundation of China,China Projects(11JDG070,11JDG140)supported by the Senior Talent Research Foundation of Jiangsu University,China Project(hsm1301)supported by the Foundation of the Jiangsu Province Key Laboratory of High-end Structural Materials,China Project(Kjsmcx2011004)supported by the Foundation of the Jiangsu Province Key Laboratory of Materials Tribology,China 

主　　题：Al-Mg aluminum alloy severe plastic deformation high pressure torsion dislocation configurations grain refinement deformation mechanism 

摘      要：Microstructure evolution and dislocation configurations in nanostructured Al–Mg alloys processed by high pressure torsion （HPT） were analyzed by transmission electron microscopy （TEM） and high-resolution TEM （HRTEM）. The results show that the grains less than 100 nm have sharp grain boundaries （GBs） and are completely free of dislocations. In contrast, a high density of dislocation as high as 1017 m^-2 exists within the grains larger than 200 nm and these larger grains are usually separated into subgrains and dislocation cells. The dislocations are 60° full dislocations with Burgers vectors of 1/2〈110〉and most of them appear as dipoles and loops. The microtwins and stacking faults （SFs） formed by the Shockley partials from the dissociation of both the 60° mixed dislocation and 0° screw dislocation in ultrafine grains were simultaneously observed by HRTEM in the HPT Al–Mg alloys. These results suggest that partial dislocation emissions, as well as the activation of partial dislocations could also become a deformation mechanism in ultrafine-grained aluminum during severe plastic deformation. The grain refinement mechanism associated with the very high local dislocation density, the dislocation cells and the non-equilibrium GBs, as well as the SFs and microtwins in the HPT Al-Mg alloys were proposed.