Twinnability of Al-Mg alloys:A first-principles interpretation  

Al-Mg合金孪晶变形的第一性原理研究（英文）

作　　者：Dong-dong ZHAO Yan-jun LI 赵冬冬;Ole Martin L?VVIK;Knut MARTHINSEN;李彦军

机构地区：[1]Department of Materials Science and Engineering,Norwegian University of Science and Technology (NTNU) [2]SINTEF Materials and Chemistry

出　　处：《Transactions of Nonferrous Metals Society of China》2017年第6期1313-1318,共6页中国有色金属学报（英文版）

基　　金：Project(222173) supported by the FRINATEK project ‘BENTMAT’ from the Research Council of Norway

摘　　要：Al-Mg alloys are considered to have potentials to form twins during deformation because Mg can reduce the intrinsicstacking fault energy?ISFE of Al.Nevertheless,twinning has rarely been found in Al-Mg alloys even subjected to various severeplastic deformation(SPD)techniques.In order to probe the twinning propensity of Al-Mg alloys,first-principles calculations werecarried out to investigate the effects of Mg and vacancies on the generalized planar fault energy(GPFE)of Al.It is found that bothMg and vacancies exhibit a Suzuki segregation feature to the stacking fault,and have the influence of decreasing the?ISFE of Al.However,?ISFE does not decrease and the twinnability parameterτa of Al does not increase monotonically with increasing Mgconcentration in the alloy.On the basis ofτa evaluated from the calculated GPFE of Al-Mg alloys,we conclude that deformationtwinning is difficult for Al-Mg alloys even with a high content of Mg.Besides,the decrease of?ISFE caused by the introduction ofMg and vacancies is supposed to have the effect of improving the work-hardening rate and facilitating the formation of bandstructures in Al-Mg alloys subjected to SPD.镁元素可以降低铝的本征层错能,因而Al-Mg合金被认为具备孪晶变形的潜力。然而在多种大变形Al-Mg合金中很难发现变形孪晶。为了探究Al-Mg合金的孪晶变形潜能,采用第一性原理计算研究镁和空位对铝广义层错能的影响。研究发现Mg和空位均具有层错Suzuki偏析特性,并且会降低Al的本征层错能。但是随着镁含量的提高,铝的本征层错能不会持续降低,孪晶特性参数τa也不会持续升高。基于Al-Mg合金的孪晶特性参数τa,我们预测即使在高固溶镁含量下,Al-Mg合金依然很难发生孪晶变形。镁和空位所引起的本征层错能的降低在一定程度上能够提高大变形Al-Mg合金的加工硬化速率并且促进变形带的形成。

关 键 词：generalized planar fault energy intrinsic stacking fault energy Suzuki segregation Mg VACANCY Al-Mg alloys 

分 类 号：TG146.21[一般工业技术—材料科学与工程]