(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中南大学 有色金属先进结构材料与制造协同创新中心，长沙 410083；
3. 中南大学 有色金属材料科学与工程教育部重点实验室，长沙 410083)
摘 要: 采用形变热处理法制备2A97铝锂合金细晶板材，利用光学显微镜、透射电镜和高温拉伸等试验方法研究中间退火温度对板材晶粒细化和超塑性的影响。结果表明：板材在室温轧制时，当变形量达到22%时，出现开裂，随着轧制温度的升高，开裂程度逐步缓解；将开轧温度提高到400 ℃、轧制变形量达到88%时，分别在240、300和400 ℃进行中间退火1 h，可解决开裂问题。但退火温度对超塑性伸长率有很大影响，当退火温度为400 ℃时，合金发生了明显部分再结晶，位错密度大幅降低，虽获得总变形量为92%的无开裂板材，由于较多的形变储能被释放，晶粒细化程度不高，伸长率仅为260%；将退火温度降低到240 ℃时，合金内部仅发生了位错运动与重新组合，保留了较高的位错密度，晶粒得到细化，伸长率高达650%。
关键字: 2A97铝锂合金；中间退火；形变热处理；变形储能；超塑性
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,
Central South University, Changsha 410083, China;
3. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China）
Abstract:Fine-grained 2A97 alloy sheets were produced by thermo-mechanical processing. The effects of intermediate annealing temperature on the grain refinement and superplasticity were investigated by optical microscopy (OM), transmission electron microscopy (TEM) and high temperature tensile test. The results show that the fracture of sheet is observed when rolling at room temperature with a reduction of 22%. With increasing the rolling temperature, the degree of cracking gradually reduces. Non-fractured sheets can be obtained by enhancing the preheating temperature to 400 ℃, and then intermediate annealing the sheets for 1 h at 240, 300 and 400 ℃, respectively, when the rolling reduction reaches 88%. But the reheating temperatures have an obvious influence on the superplastic elongation. When the reheating temperature is 400 ℃, the obvious recrystallization occurs, which reduces the density of dislocations. Though non-fractured sheets with a total reduction of 92% are obtained, the superplastic elongation only reaches 260%, because of more deformation stored energy released and low grain refinement. High density of dislocations and a superplastic elongation of 650% are obtained when the reheating temperature decreases to 240 ℃, during which only the movement and reconfiguration of dislocations happen.
Key words: 2A97 aluminum-lithium alloy; intermediate annealing; thermo-mechanical processing; deformation stored energy; superplasticity
