As a new generation of Al-Zn-Mg-Cu alloy, 7085 aluminum alloy is a promising structural material in the field of aerospace industry. However, research on its thermal stability is still lacking. In the present work, thermal exposure was carried out on the T7452-treated 7085 aluminum alloy under different temperatures (100 °C, 125 °C, 150 °C and 175 °C) for 500 h. Variations of tensile properties and hardness were exhibited. The microstructure, nano-scale precipitates and fracture characteristics of the alloy were investigated using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that with the increase of exposure temperature, the strength and hardness increase first and then decrease while the elongation and the reduction of area increase continuously as compared to those of the non-thermal exposed alloy. The transformation from η′ phase to η phase during thermal exposure occurs continuously during thermal exposure. In addition, as the exposure temperature increases, the average dimensions of precipitates and the average spacing of neighbor precipitates become larger. The influence of precipitates on mechanical properties of the alloy is discussed.

作为新一代的Al-Zn-Mg-Cu合金，7085铝合金在航空航天领域是一种很有前途的结构材料。但是，仍然缺乏关于其热稳定性的研究。在当前工作中，在不同温度（100°C，125°C，150°C和175°C）下，对经过T7452处理的7085铝合金进行热暴露500 h。表现出拉伸性能和硬度的变化。使用光学显微镜（OM），扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究了合金的微观结构，纳米级析出物和断裂特性。结果表明，随着曝光温度的升高，与非热暴露合金相比，强度和硬度先增加然后降低，而伸长率和面积减少率则连续增加。在热暴露期间从η'相到η相的转变在热暴露期间连续发生。另外，随着曝光温度的升高，析出物的平均尺寸和相邻析出物的平均间距变大。讨论了析出物对合金力学性能的影响。