新型7056铝合金双级时效的显微组织和性能

Microstructure and properties of two-step aged novel 7056 aluminum alloy

采用力学性能和电导率测试以及透射电子显微镜组织等观察分析新型7056铝合金双级时效制度下的性能和显微组织。结果表明：第二级时效处理后,合金基体沉淀析出相长大粗化,晶界析出相逐渐呈断续分布状态,无析出带随时间的延长而变宽;经第二级150℃、12 h时效后,合金由GP区和η相构成,析出相的尺寸为7~9 nm,并出现明显的无析出带;随着第二级时效时间的延长,合金电导率逐渐升高,屈服强度先增大后减小;合金经（110℃、6 h）＋（150℃、14 h）双级时效处理后,屈服强度达到650 MPa,电导率为21.72 MS/m,表现出优异的综合性能。

The properties and microstructure of two-step aged Al-9.73Zn-1.98Mg-1.76 Cu aluminum alloy were studied by using of measuring properties and electrical conductivity and TEM analysis. The results show that matrix precipitates growth and coarsening, grain boundary phases distribute discontinuous, and precipitation free zone（PFZ） become broader with increasing the second ageing time. The second（150 ℃, 12 h） aged alloy consists of GP zone and η′ phase, the size of precipitates is between 7-9 nm, and PFZ can be found apparently. The electrical conductivity increases with increasing the second step ageing time, while yield strength increases firstly, and then reduces. Alloy aged at（110 ℃, 6 h）＋（150 ℃, 14 h） can obtain the yield strength of 650 MPa, and electrical conductivity of 21.72 MS/m, which shows good performance matching.