(1. 中南大學(xué)材料科學(xué)與工程學(xué)院，長沙 410083；
2. 北京宇航系統(tǒng)工程研究所，北京 100076)
摘 要: 研究時效前固溶處理、預(yù)變形等對一種新型超高強(qiáng)Al-Cu-Li-X合金板材力學(xué)性能和顯微組織的影響。結(jié)果表明：500~540 ℃固溶40 min時，隨固溶溫度的提高，合金的時效強(qiáng)度呈現(xiàn)先升高后持平的趨勢，且在520 ℃時強(qiáng)度略有下降；510 ℃固溶20~180 min時，隨固溶時間延長，合金的時效強(qiáng)度則呈現(xiàn)先升高后降低的趨勢；(510 ℃, 40 min)固溶處理后的合金具有最高的時效強(qiáng)度。不同固溶處理合金的強(qiáng)度變化主要受固溶階段第二相粒子的回溶程度、再結(jié)晶晶粒形態(tài)及長大趨勢和過燒的共同影響。合金強(qiáng)化相為大量T1相(Al2CuLi)、部分θ′相(Al2Cu)和少量S′相(Al2CuMg)，預(yù)變形可促進(jìn)T1相細(xì)小彌散析出，但抑制θ′相及S′相的析出。預(yù)變形量小于6%的預(yù)變形可有效提高合金的時效強(qiáng)度，但當(dāng)預(yù)變形量大于6%之后，合金強(qiáng)度的增量逐漸減少。
關(guān)鍵字: 鋁鋰合金；固溶處理；預(yù)變形；力學(xué)性能；顯微組織
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Beijing Institute of Aerospace Systems Engineering, Beijing 100076, China）
Abstract:Effect of solution treatment and pre-deformation before aging on tensile properties and microstructures of a new ultra-high strength Al-Cu-Li-X alloy were investigated. The result shows that, as solution-treated for 40 min at 500-540 ℃, the strength of the aged alloy increases firstly then keeps a relatively same strength with increasing the solution temperature except at 520 ℃. As solution-treated at 510 ℃for 20-180 min, the strength of the aged alloy increases firstly then decreases. The aged alloy with solution treatment of (510 ℃, 40 min) possesses the highest strength. The strength variation corresponding to various solution treatment is comprehensively affected by the secondary particle dissolution, grain structure, grain growth and overburning. The strengthening precipitates of the aged alloy consist of a large number of T1 phase (Al2CuLi), some θ′ phase (Al2Cu) and a small amount of S′ phase (Al2CuMg). Pre-deformation can promote the precipitation of T1 phase, but restrain the precipitation of θ′ and S′ phases. When the pre-deformation is lower than 6%, the strength increases substantially with increasing pre-deformation. But when the pre-deformation is larger than 6%, the strength increment caused by pre-deformation is reduced.
Key words: Al-Li alloy; solution treatment; pre-deformation; tensile property; microstructure
