(1. 西北有色金属研究院，西安 710016；2. 云南大学 材料科学与工程学院，昆明 650091)
摘 要: 在Gleeble-3500热模拟试验机上对Ti-25Al-14Nb-2Mo-1Fe合金进行等温恒应变速率压缩试验，研究在变形温度950~1100 ℃、变形速率0.001~1 s-1、最大变形程度为50%条件下合金的热变形行为，分析变形温度和变形速率对热变形组织演变规律的影响。结果表明：Ti-25Al-14Nb-2Mo-1Fe合金的流变应力对变形温度和变形速率均较为敏感，其流变应力—应变曲线具有应力峰值、流变软化和稳态流变特征。变形温度和变形速率对合金热变形组织演变影响较大。在变形温度为950和1050 ℃、变形速率为0.001~1 s-1条件下，随变形速率的降低，合金中片层组织球化，动态再结晶发生程度增大；在变形速率为0.1 s-1、变形温度为950~1100 ℃条件下，随变形温度的升高，合金中动态再结晶发生程度明显增大；在变形温度为950 ℃、变形速率为1 s-1条件下，合金中易形成绝热剪切带。
关键字: Ti2AlNb基合金；高温塑性变形；组织演变；动态再结晶；流变应力
（1. Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China;
2. School of Material Science and Engineering, Yunnan University, Kunming 650091, China）
Abstract:The hot deformation behavior of Ti-25Al-14Nb-2Mo-1Fe alloy was investigated at deformation temperatures between 950 and 1100 ℃ with strain rate between 0.001 and 1 s-1, and the highest reduction of 50% by using isothermal compression test on Gleeble-3500 simulator. The effects of deformation temperature and strain rate on the microstructure evolution during hot working were analyzed. The results show that the flow stress of the alloy is sensitive to the variation of deformation temperature and strain rate. The stress—strain curves exhibit a peak flow stress, flow softening and steady state flow behavior. The microstructure evolution is greatly affected by deformation temperature and strain rate. The degree of lamellar globularization and dynamic recrystallization increases with the strain rate decreasing in the strain rate range of 0.001-1 s-1 at 950 and 1 050 ℃. The degree of dynamic recrystallization increases with deformation temperature increasing in the range of 950-1 100 ℃ at 0.1 s-1. The shear deformation bands are easy to occur at 950 ℃ and 1 s-1, which should be avoided during hot working.
Key words: Ti2AlNb-based alloy; hot plastic deformation; microstructure evolution; dynamic recrystallization; flow stress
