挤压态AZ31镁合金变形组织演变机制  

Microstructure evolution mechanism of extruded AZ31 magnesium alloy during deformation

作　　者：何杰军[1,2] 吴鲁淑[3] 

机构地区：[1]贵州理工学院材料与冶金工程学院,贵州贵阳550003 [2]重庆大学材料科学与工程学院,重庆400044 [3]贵州理工学院机械工程学院,贵州贵阳550003

出　　处：《材料热处理学报》2017年第1期43-49,共7页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51501045);贵州省自然科学基金(黔科合J字[2015]2067号);贵州理工学院高层次人才科研启动经费项目(XJGC20141102);黔科合人才团队(2015)4008号

摘　　要：研究了挤压态AZ31镁合金在压缩过程中的组织变化及其演变机制,探讨了孪生对加工硬化的影响。结果表明,当应变量小于4%时,孪晶含量随应变增大而增多;此后,随应变增加,孪晶含量反而逐渐减少,显微组织分析表明发生了退孪生现象。但织构分析表明,镁合金在压缩过程中并没有发生退孪生。孪晶长大与合并模型被用于解释组织分析显示的孪晶产生和消失现象。在挤压态镁合金的压缩过程中,孪晶的长大与合并导致基体几乎被消耗完毕,大部分基体转变成了孪晶组织,孪晶合并成片,以至于在显微组织观察中产生了孪生先产生后消失的假象。研究还表明,在孪生过程中镁合金的晶体取向发生86.3°的转变,使得镁合金从软取向变成了硬取向,这种取向的转变是镁合金压缩变形过程加工硬化的主要原因。Microstructure evolution and its mechanism of an extruded AZ31 magnesium alloy during compressive deformation were investigated.The results show that when the strain is lower than 4%,the volume fraction of twins increases with the increasing of strain,however,it decreases with the increasing of strain after that.Textures analysis shows no detwinning can occur during this process.A schematic model of twin growth and coalescence is conducted to explain the twins＇ appearance and disappearance.During deformation,the twin growth and coalescence can lead all the matrices nearly to be consumed,which leading to an analogous detwinning phenomenon observed in the optical micrographs.The essential of microstructure evolution during this process is the disappearance of the initial matrices.And also,the roles of twinning on strain hardening were investigated.During deformation,the orientation is transferred about86.3°,leading to an orientation transformation from ＂soft ＂to ＂hard ＂.This transformation is mainly responsible for samples ＇strain hardening during compression.

关 键 词：镁合金 孪生 织构 塑性变形 

分 类 号：TG146.2[一般工业技术—材料科学与工程]