(中南大学 材料科学与工程学院， 长沙 410083)
摘 要: 采用光学显微镜、 透射电子衍射和扫描电子衍射显微分析技术， 结合力学性能检测和电导率测定的方法， 研究双级固溶温度和时间对7A55铝合金板材力学性能的影响。 结果表明： 最佳双级固溶制度为450 ℃, 90 min+485 ℃, 40 min。 采用该固溶制度经120 ℃, 24 h时效后， 板材的拉伸力学性能达到σb＝648.4 MPa, σ0.2＝629.6 MPa及δ＝11.9%。 第一级固溶制度是影响板材力学性能的主要因素， 最佳固溶温度为450 ℃。 在450 ℃进行第一级固溶后， 样品发生了较强的回复， 由于降低了再结晶驱动力， 第二级高温固溶在获得较高的合金元素过饱和度的同时， 仅发生较少的再结晶， 从而在随后的时效过程中产生更高的析出强化效应。
关键字: 7A55铝合金； 再结晶； 回复； 双级固溶； 力学性能
microstructures and mechanical properties of
7A55 aluminum alloy
（School of Materials Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: The effects of temperature and time of two-stage solution on mechanical properties of 7A55 aluminium alloy sheet were investigated by optical microscopy, TEM and SEM analyses and tensile testing and electrical conductivity test. The optimal two-stage solution treatment is 450 ℃, 90 min+485 ℃, 40 min. The mechanical properties σb, σ0.2 and δ reach 648.4 MPa, 629.6 MPa and 11.9%, respectively, after aging at 120 ℃ for 24 h. The results show that the first stage solution is crucial to the mechanical properties, and the optimal temperature is 450 ℃. The extensive recovery occurs after the first stage solution at 450 ℃, which reduces the driving force of recrystallization. Consequently, higher alloying elements supersaturation in matrix is obtained at the second stage high temperature solution and only little recrystallization happens. As a result, a better precipitation strengthening effect in subsequent aging is attained.
Key words: 7A55 aluminum alloy; recrystallization; recovery; two-stage solution; mechanical properties
