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研究了双级时效的预时效阶段及高温短时回归时效处理对AA7050合金组织和性能的影响。结果表明,AA7050合金时效硬化效果明显,预时效温度越高,硬化速率越快;在不高于135℃下时效,具有较好的抗过时效能力。135℃下预时效12 h后,晶内组织以GP区为主,且晶界平衡相细小连续,无明显晶界无析出带,合金强度处于亚峰值状态。170℃高温二级时效处理时,随时效时间延长,合金强度先上升后下降;时效2 h时,综合力学性能最佳,晶内主要强化相为GP区和η’相,晶界为不连续的η相,伴随10～20 nm的晶界无析出带,随二级时效时间延长,晶内η’相大量向η相转化,强度迅速下降。
The effects of pre-aging stage of dual-stage aging and high-temperature short-term regression aging on the microstructure and properties of AA7050 alloy were studied. The results show that the AA7050 alloy has obvious aging hardening effect. The higher the pre-aging temperature is, the faster the hardening rate is. The aging resistance is better than 135 ℃. After pre-aging at 135 ° C for 12 h, the intragranular structure was dominated by GP, and the equilibrium phase in the grain boundary was fine and continuous, with no obvious precipitation of grain boundaries and the strength of the alloy in the sub-peak state. When aging at 170 ℃ for 2 h, the strength of the alloy first increases and then decreases with the aging time. The mechanical properties are the best when the aging time is 2 h. The main strengthening phases are GP zone and η ’phase, and the grain boundaries are discontinuous Η phase with no precipitation band at 10 ~ 20 nm. With the increase of secondary aging time, η ’phase in the ingot was transformed into a large amount to η phase, and its strength decreased rapidly.