中文摘要：

采用室温拉伸、抗晶间腐蚀性能测试（IGC）、光学显微镜（OM）及透射电镜（TEM）观察等手段,研究3种回归冷却速率（17℃/s,3℃/s,0.02℃/s）对回归再时效（RRA）态7050铝合金力学性能及抗晶间腐蚀性能的影响。结果表明,在快冷（17℃/s）条件下,回归态组织的过饱和固溶体含有较高的空位浓度,有利于再时效析出,再时效态组织的晶界析出相为较粗大的非连续颗粒,并有较宽的无沉淀析出带（PFZ）;慢冷（3℃/s或0.02℃/s）条件下,在冷却过程中晶界和晶内均析出了微小的第二相,导致固溶体内空位浓度降低,影响再时效析出,使得再时效态组织的晶界析出相颗粒粗细不均匀,无沉淀析出带变窄。相应地,随冷却速率降低,合金的拉伸强度单调下降,抗晶间腐蚀性能先下降,后略有升高。

英文摘要：

The effects of retrogression cooling rate （17℃/s, 3 ℃/s and 0.02℃/s） on the mechanical properties and resistance to intergranular corrosion of 7050 aluminum alloy were investigated by tensile testing, intergranular corrosion （IGC） testing, optical microscopy（OM） and transmission electron microscopy（TEM）. The results show that by quenching at the rate of 17 ℃/s （quick cooling）, the supersaturated solid solution as retrogression contains high vacancy concentration which is beneficial to re-aging. So, there are wider precipitate free zones （PFZ） and coarser discontinuous precipitates at grain boundaries in the re-aging microstructure. However, slow cooling at the rates of 3 ℃/s and 0.02℃/s, some of fine particles of the second phase precipitate gradually on grain boundaries and in grains, which leads to decreasing the vacancy concentration generally. Precipitation is difficult during re-aging, and the precipitate size at the boundary is not uniform besides ambiguous precipitation free zones （PFZs）. Accordingly, with the decrease of the cooling rate, the tensile strength decreases monotonously, but the resistance to corrosion decreases firstly and then increases slightly.