(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中南大学 有色金属材料科学与工程教育部重点实验室，长沙 410083；
3. 湖南交通职业技术学院 机电工程系，长沙 410004)
摘 要: 采用光学金相显微镜、扫描电镜、透射电镜、硬度测试、拉伸实验以及盲孔法测算残余应力等方法研究循环加载时效对Al-Cu铸造合金材料显微组织、力学性能及残余应力的影响。结果表明：淬火态Al-Cu铸造合金中存在较大的残余应力，在人工时效过程中可诱发θ′强化相的应力位向效应；而-40~80 MPa、83 Hz、40 min的循环加载处理可使峰值时效态Al-Cu铸造合金的残余应力降低到0.28σ0.2，其引起的微小塑性变形产生的大量位错组态诱发θ′相非均匀形核，提高了形核率，起到了细化析出相尺寸的作用，且抑制了θ′相析出的应力位向效应，从而提高了Al-Cu铸造合金材料的力学性能。
关键字: 铝合金；循环加载；时效；显微组织；力学性能；残余应力
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Materials Science and Engineering,
Ministry of Education, Central South University, Changsha 410083, China;
3. Department of Mechanical and Electrical Engineering, Hunan Communication Polytechnic, Changsha 410004, China）
Abstract:Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), hardness test, tensile test, and hole-drilling method of measuring residual stress were used to study the influence of cyclic loading aging on the microstructure, mechanical properties and residual stresses of Al-Cu casting alloy. The results show that, the stress orientation effect of θ'''' precipitates, which occurs during the artificial aging, is induced by the high residual stress of the quenched Al-Cu casting alloy. However, the residual stress can be reduced to 0.28σ0.2 by cyclic loading at -40-80 MPa, 83 Hz and 40 min. During this process, the dislocations resulted from the micro-plastic deformation can facilitate the heterogeneous nucleation of θ'''' phase and the nucleation, which results in the refinement of precipitates and the restraint of the stress orientation of θ'''' phase. Therefore, the mechanical properties of the Al-Cu casting alloy treated by the cyclic loading aging are improved.
Key words: aluminium alloy; cyclic loading; aging; microstructure; mechanical properties; residual stress
