Ta-7.5％W在退火过程中的组织和织构演变

通过金相组织观察、透射电子显微镜(TEM)及显微硬度测试,研究冷轧变形量为95％的Ta-7.5％W合金箔材在1 050,1 200和1 360℃退火时的组织和性能变化,并采用取向密度函数(ODF)分析在此过程中其织构演变规律.对其实验结果进行研究发现:冷轧态Ta-7.5％W合金硬度为HV 300,经1 360℃退火后硬度迅速减小,说明此时合金已发生回复再结晶.轧制后的Ta-7.5％W合金箔材具有各向异性,在轧面∥{111}取向上形成位错胞亚结构,在轧面∥{100}取向上形成了形变带,冷轧态的主要织构为{001}〈110〉,{112} 〈110〉和{110}〈110〉织构;在1 200℃退火时,在轧面∥{111}取向上,再结晶通过亚晶界迁移、亚晶长大形核,而在轧面∥{100}取向上,主要是通过亚晶转动、聚合形核;{001}〈110〉织构增强,{112}〈110〉织构减弱;在1 360℃退火时,{001}〈110〉织构急剧减弱,{111}〈112〉织构增强.

Microstructures and textures evolution of Ta-7.5%W during annealing process

The organization and performance evolution of Ta-7.5%W at 1 050,1 200 and 1 360 ℃ were investigated by microstructure observation,transmission electron microscope(TEM) and hardness tests,and the texture evolution was investigated by orientation density function(ODF).It was found that after 1 360 ℃ annealing the hardness decreases rapidly from HV 300 to HV 240,and the recovery recrystallization occurs.Ta-7.5%W is anisotropic;the dislocation substructure appears in {111} orientation and the deformation zone appears in {100} orientation.The main textures of cold-rolled Ta-W alloy are {001},{112} and {110}.As the annealing temperature is 1 200 ℃,the recrystallization nucleation is mainly through the migration of the subgrain boundary and the growth of the subgrain in {111} orientation,while the recrystallization nucleation is mainly through the rotation and polymerization of the subgrain in {100} orientation;the texture of {001} increases and the texture of {112} decreases.While annealing at 1 360 ℃,the texture of {001} decreases rapidly,and the texture of {111} increases.