Processing Maps for Hot Working Behavior of a PM TiAl Alloy

• 来源期刊: 材料科学技术学报：英文版
• 学科: 工学
• 关键词: TiAl合金 热变形行为 加工图 热工 动态再结晶 不稳定性 温度范围 流动应力
• 年，卷（期）: 2011,（10）
• 页码范围: 893-898
• 页数: 6页
• 分类号: TG146.2|TQ323.4
• 语种: 英文

摘要

The hot deformation behavior of a Ti-47Al-2Cr-2Nb-0.2W-0.15B （at%） titanium aluminide alloy fabricated by pre-alloyed powder metallurgy has been investigated by using the hot compression tests in the temperature range from 950℃ to 1300℃ and at the strain rates between 10-3 s-1 and 10 s-1. The processing maps have been established to evaluate the optimum hot processing conditions and reveal the instability regions. It is found that the flow stress of the investigated alloy is a strong function of the temperature and the strain rate, The investigated alloy has the optimum hot-working condition at 950℃ and 10-3 s-1, since the material undergoes dynamic recrystallization to produce a fine-grained microstructure. At 1250℃ and 10-3 s-1, the alloy exhibits superplastic deformation. At 2300℃ and 10-1 s-1, the cyclic dynamic recrystallization with high temperature grain coarsening takes place. The material undergoes flow instabilities at lower temperatures and higher strain rates, as predicted by the instability criterion. The processing maps demonstrate that the strain significantly affected the instability regions. The manifestations of the instabilities have been observed in the form of microvoids, wedge cracks, and surface fractures.