(1. 中南大学 轻合金研究院，长沙 410083；
2. 中南大学 材料科学与工程学院，长沙 410083；
3. 中南大学 高性能与复杂制造国家重点实验室，长沙 410083)
摘 要: 采用光学显微及透射电子显微、拉伸力学性能、维氏硬度等测试技术，研究Al-Cu-Li合金在蠕变时效过程中拉伸性能演变规律与微观组织特征。结果表明：在蠕变时效过程中，合金的硬度和强度呈现先升高，到达峰值之后再缓慢下降的趋势。其中CA2试样(2%预变形再进行蠕变时效)在16 h达到了蠕变时效硬度与强度峰值，比CA1试样(不预变形直接进行蠕变时效)提前了4 h，且CA2试样的峰值区域更为明显。相比于CA1试样，CA2试样的硬度和强度提高，伸长率降低。在峰值蠕变时效状态下，CA1试样最大晶间腐蚀深度为180.6 μm，腐蚀等级为4级；CA2试样最大晶间腐蚀深度为92.0 μm，腐蚀等级为3级。TEM结果表明：CA1试样中以细小致密的θ′相为主，晶内可见少量T1相；CA2试样由于T1相在蠕变时效初期时存在析出优势，晶内析出大量T1相的同时，伴随着细小的θ′相，且CA2试样T1相在亚晶界处的富集程度要低于CA1试样的。
关键字: AL-Cu-Li合金；蠕变时效；力学性能；晶间腐蚀；T1相
（1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083, China）
Abstract:The tensile properties and microstructure characteristics of Al-Cu-Li alloy during creep aging were studied by optical microscopy and transmission electron microscopy, tensile mechanical properties and Vickers hardness. The results show that the hardness and tensile strength increase gradually to the maximum, and then decrease slowly during creep aging. The maximum hardness and tensile strength are obtained after the CA2 sample (creep aging after 2% pre-stretching) creep aging for 16 h, which reaches the maximum values than CA1 sample (creep aging without pre-stretching) earlier about 4 h. When compared with CA1 samples in the creep aging, the peak value is sharper in the CA2 samples and possess higher hardness and tensile strength, but lower elongation. Under the condition of peak creep aging, the maximum intergranular corrosion depth of CA1 specimen is 180.6 μm, and the corrosion level is 4. The maximum intergranular corrosion depth of the CA2 specimen is 92.0 μm and the corrosion level is 3. TEM results show that the CA1 sample is dominated by small, dense θ′ phases, and a small amount of T1 phases can be seen in the crystal. For the sake with a precipitation advantage at the initial stage in the CA2 sample, a large number of T1 phases are precipitated in the crystal accompanying with a small θ′ phase, and the enrichment of precipitated T1 at the sub-crystal boundary is lower than that in the CA1 sample.
Key words: Al-Cu-Li alloy; creep aging; mechanical property; intergranular corrosion; T1 phase
