Microstructure Optimization and Comprehensive Property Improvement of Al-4.47Zn-2.13Mg-1.2Cu Alloy by Non-isothermal Aging Treatment

In order to thoroughly explore the relationship between precipitation and mechanical behavior in a precipitation-strengthened Al-4.47Zn-2.13Mg-1.2Cu wrought alloy plate under non-isothermal aging treatment (NIA), performance testing and transmission electron microscopy have been conducted. For the heating aging treatment, the mixture of the Guinier–Preston zone and η'  and η precipitates distribute uniformly everywhere with a narrow precipitate-free zone (PFZ) at the grain boundaries. The yield strength, ultimate tensile strength, and elongation of the Al alloy after (100–200°C, 20°C/h) were increased by 6.6%, 12.8%, and 9% as compared with those samples after T6 treatment. Because the bulky precipitation with a wider PFZ under the cooling aging treatment was obtained, the strength of the alloy was slightly lower. Meanwhile, the time spent on NIA can be decreased by about 70% compared that for T6 treatment. Current results indicate that NIA could improve the mechanical property and production efficiency with less energy consumption.