Microstructural Evolution of NiTi47.7Cu6.3 Alloy during Hot Deformation

• 来源期刊: 材料科学技术学报：英文版
• 学科: 工学
• 关键词: 形状记忆合金 组织演变 变形过程 扫描电子显微镜 变形温度 微观结构 应变诱导 光学显微镜
• 年，卷（期）: 2011,（10）
• 页码范围: 951-960
• 页数: 10页
• 分类号: TG139.6|TG146.21
• 语种: 英文

摘要

In the present work, the hot workability and microstructural evolution of NiTi47.TCu6.3 （at.%） shape memory alloy were investigated by using wedge-rolling test. The wedge specimens were subjected to hot rolling at the temperatures of 700-1000℃. The microstructural evolutions at the strains of 0.05, 0.15, 0.2, 0.25 and 0.3 were then characterized by optical microscopy and scanning electron microscopy （SEM） as well as energy dispersive spectrometry （EDS） technique. Depending on the deformation temperature and strain, the dynamic recrystallization （DRX） could occur, leading to the refining of the microstructure. At low temperatures of 700 and 800℃ there was no sign of DRX at all studied strains. At these temperatures, the formed fine needle-like precipitates pinned the grain boundaries and prevented them from bulging/migration. By contrast, at higher temperatures of 900 and 1000℃, the DRX took place at the critical strains lower than 0.25 and 0.15, respectively. However, at higher temperatures, strain-induced-boundary-migration （SIBM） mechanism resulted in the formation of DRX grains.