【摘要】 Al-Cu-Li合金作为航空航天工业中一种前景广阔的结构材料，其热稳定性在实际应用中发挥着重要作用。本研究对T85态的Al-Cu-Li合金在一系列温度（100～300℃）下进行了500 h的暴露处理，并通过维氏硬度、电导率和拉伸测试对其性能进行了评估。结合扫描电子显微镜（SEM）和透射电子显微镜（TEM）分析了不同热暴露温度下的微观结构演变。结果表明，热暴温度低于150℃时，合金具有良好的热稳定性，这与T1（Al₂CuLi）相的直径和数密度不断增加相关。当热暴露温度介于150～200℃时，T1相逐渐被粗大的θ’-Al₂Cu和S-Al₂CuMg取代；同时，断续的晶界析出物（GBPs）和宽的无析出区（PFZs）利于沿晶断裂，使合金呈现出沿晶-穿晶混合断裂，导致硬度和强度的降低和延伸率的增加。热暴露温度高于250℃时，T1相全部溶解，形成了粗大的T2（Al₆Cu（Li, Mg）₃）和C相，从而导致合金的强度下降，但延伸率和电导率却表现出相反的趋势。更多还原

【Abstract】 As a promising structural material in the aerospace industry, the long-term thermal stability of Al-Cu-Li alloys plays an important role in practical applications. In this study, the T85-treated AlCu-Li alloy subjected to thermal exposure at a range of temperatures（100～300 ℃） for 500 h, is evaluated by Vickers hardness, electrical conductivity and tensile tests. The microstructure evolution at different heat exposure temperatures is analyzed by a combination of scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The results show that excellent thermal stability in strength is obtained below 150 ℃, which can be related to the increasing diameter and number density of the T1（Al₂CuLi） phase. In the 150～200 ℃ window, the T1 phase is gradually replaced by coarse θ’-Al₂Cu and S-Al₂CuMg with increasing temperature. Simultaneously, discontinuous grain boundary precipitates（GBPs） and soft precipitation-free zones（PFZs） lead to intergranular ductile fracture dominance, exhibiting mixed ductile and brittle fracture. At temperatures above 250 ℃, the T1 phase is completely dissolved and coarse T2（Al₆Cu（Li, Mg）₃） and C phases are formed. This leads to a dramatic decrease in the strength, while elongation and conductivity show an opposite trend.更多还原