(1. 中南大學 材料科學與工程學院，長沙 410083；
2. 中南大學 有色金屬材料科學與工程教育部重點實驗室，長沙 410083；
3. 湖南交通職業(yè)技術學院 機電工程系，長沙 410004)
摘 要: 采用光學金相顯微鏡、掃描電鏡、透射電鏡、硬度測試、拉伸實驗以及盲孔法測算殘余應力等方法研究循環(huán)加載時效對Al-Cu鑄造合金材料顯微組織、力學性能及殘余應力的影響。結果表明：淬火態(tài)Al-Cu鑄造合金中存在較大的殘余應力，在人工時效過程中可誘發(fā)θ′強化相的應力位向效應；而-40~80 MPa、83 Hz、40 min的循環(huán)加載處理可使峰值時效態(tài)Al-Cu鑄造合金的殘余應力降低到0.28σ0.2，其引起的微小塑性變形產生的大量位錯組態(tài)誘發(fā)θ′相非均勻形核，提高了形核率，起到了細化析出相尺寸的作用，且抑制了θ′相析出的應力位向效應，從而提高了Al-Cu鑄造合金材料的力學性能。
關鍵字: 鋁合金；循環(huán)加載；時效；顯微組織；力學性能；殘余應力
（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
