Ta-7.5%W合金箔材冷轧过程中的位错结构演变  

EVOLUTION OF DISLOCATION MICROSTRUCTURES IN Ta-7.5%W ALLOY FOILS DURING COLD-ROLLING

作　　者：陈畅[1] 汪明朴[1] 王珊[1] 贾延琳[1] 左波[1] 夏福中[1] 

机构地区：[1]中南大学材料科学与工程学院,长沙410083

出　　处：《金属学报》2011年第8期984-989,共6页Acta Metallurgica Sinica

基　　金：国家高技术研究发展计划资助项目2006AA03Z517~~

摘　　要：本文详细研究了Ta-7.5%W合金中取向为45°立方旋转织构{001}〈110〉方向的晶粒在冷轧变形过程中的位错结构和显微硬度演变规律.结果发现,当冷轧变形10%时,合金中形成了典型的bcc金属冷变形的位错结构,包括位错偶极子、位错反应形成的"剪刀"型位错以及位错碎片亚结构等;随着变形的进一步进行,其中一种晶粒中初期形成的高密度位错墙在变形后期形成微带组织,而在另一种晶粒中形成了典型的位错胞结构.由经典位错理论的能量分析,位错缠结形成的网络结构可以弛豫形成低能的位错胞结构.在Ta-7.5%W合金中形成微带组织并不需要在晶粒中预先存在位错胞结构,但是此时合金的晶粒中必须有高密度位错墙结构,位错密度达到10^(14)/m^2左右.显微硬度测试表明这两种晶粒在冷轧过程中的加工硬化率不同,与含位错胞组织的晶粒相比,含微带组织晶粒的加工硬化率更高.The most common texture formed in rolled bcc metals is 45°rotated cubic {001}〈110〉 the detailed deformation structure and microhardness of these grains in cold-rolled Ta-7.5%W alloy foils were carefully investigated.It was found that when cold reduction was 10%,the typical cold deformation microstructures were found in the grains,including dislocation dipoles,a ＂scissors＂ type dislocation reaction and dislocation debris.As the reduction increased,high dense dislocation walls were formed firstly and microbands formed subsequently in one kind of grains while typical dislocation cells were formed in another kind of grains.Based on energy analysis,dislocation mesh structures would relax into dislocation cells because the elastic energy of the dislocation cells is always lower than that of the dislocation mesh.It is probable that the microbands are derived from the high dense dislocation walls rather than dislocation cells while the dislocation density in the grains must reach a critical value which is about 10^（14）/m^2 in Ta-7.5%W alloy.The microhardness test showed that the work hardening rates were different in these grains.Compared with grains with cell structures,the work hardening rate was higher in grains with microbands.

关 键 词：TA-W合金 冷轧 箔材 织构 位错结构 

分 类 号：TG146.2[一般工业技术—材料科学与工程]