(1. 华中科技大学 材料科学与工程学院 材料成形与模具技术国家重点实验室，武汉 430074；
2. 上海航天设备制造总厂，上海 200245)
摘 要: 本文对比研究了传统形变热处理(TMT)与基于脉冲电磁场作用的形变热处理(TMTP)，后者工艺路径为固溶淬火-预拉伸-不发生形变的脉冲电磁场作用-人工时效。在脉冲电磁场作用过程中，通过模具压板的位移约束以保证试样不发生塑性变形。结果表明：两种形变热处理都能显著提升退火态试样的屈服强度，其中TMTP条件下的屈服强度提升幅度更大，达254.3%。同时，TMTP工艺下试样的伸长率略大于TMT工艺下试样的伸长率。透射电镜结果表明，致密分布的析出相保证了两种形变热处理试样的强度。扫描电镜分析表明，TMT试样断口形貌为典型的沿晶断裂模式，能观察到少量的韧窝。TMTP试样断口也是沿晶断裂模式，但是韧窝数量较多。通过晶间析出相与晶界强度之间关系揭示了TMTP试样塑性提高的机理。
关键字: 铝锂合金；形变热处理；脉冲电磁场；晶界析出相；韧窝
（1. State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;
2. Shanghai Aerospace Equipments Manufacturer, Shanghai 200245, China）
Abstract:The thermomechanical treatment (TMT) and thermomechanical treatment combined with pulsed electromagnetic field (TMTP) were carried out. The latter process is solution treatment and quench, following by pre-stretching, pulsed electromagnetic field treatment without deformation, and artificial aging. During the pulsed electromagnetic field treatment, the displacement constraint of the die plate is used to ensure that no plastic deformation occurs in the specimen. The results show that the two thermomechanical treatment processes can significantly increase the yield strength of the as-annealed specimens, and the increment of yield strength of the specimen under TMTP condition is greater, which reaches 254.3%. At the same time, the elongation of the TMTP specimen is slightly larger than the TMT one. TEM results show that the densely distributed precipitates ensure the strength of the specimens under two TMT conditions. SEM results show that the fracture morphology of the TMT specimen is typical intergranular fracture combined with a small number of dimples, while the TMTP one is intergranular fracture combined with more dimples. Through the relationship between the grain boundary precipitates and the strength of the grain boundary, the mechanism of the plasticity improvement for TMTP specimen was revealed.
Key words: Al-Li alloy; thermomechanical treatment; pulse electromagnetic field; grain boundary precipitates; dimples
