中文摘要：

采用光学、扫描电镜和高温拉伸等手段，研究了不同时效制度对2A97铝锂合金晶粒细化和超塑性的影响。结果表明：试验合金在300～400℃时效可获得尺寸大于0．8μm的第二相粒子，其中400℃×48h过时效处理获得的第二相分布更均匀、体积分数更大，经过相同工艺轧制和再结晶退火后，获得的晶粒最为细小。在温度460～490℃，应变速率为1．0×10^-3～2．5×10^-3s^-1的条件下进行高温超塑性拉伸，其中在490℃、2．0×10^-3s^-1变形条件下获得伸长率最大，达到850％。

英文摘要：

By means of optical microscopy （ OM）, scanning electron microscopy （SEM） and high temperature tensile machine, the effect of aging treatment on grain refinement and superplasticity of 2A97 Al-Li alloy was investigated. The results show that the second phase particles with size of larger than 0.8 μm are obtained when aged at 300-400 ℃ ; especially when aged at 400 ℃ ×48 h, the second phase particles are distributed more uniformly with a larger volume fraction and the grain size is finest under the same rolling process and recrystallization annealing process. The superplastic tensile test was carried out at 460-490 ℃ when the strain rate from 1.0 ×10^-3 s ^-1 to 2.5 × 10^-3 s ^-1 ,and the best elongation of the specimens reaches 850% at 490 ℃ and the strain rate of 2.0 ×10^-3 s^-1.