(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 通过力学性能测试和显微组织观察研究一种新型Al-Cu-Li合金在不同时效制度下组织和性能之间的关系。结果表明：该合金具有强度高、各向异性小、热稳定性好等特点；该合金在T6和T8状态下强化相均为T1相和θ′相，其中T1相起主要作用；时效前的预变形促进T1相析出，显著提高合金强度，变形量控制在5%左右时，合金具有最好的强塑性匹配，抗拉强度达623.6 MPa，伸长率为10.2%；固溶淬火后进行先低温后高温的双级时效制度并未提高合金强度，但稍微提高了合金塑性；合金在T6、T8状态下强度各向异性均保持在5%以下；该合金在不高于150 ℃热暴露时，表现出良好的热稳定性，但高于150 ℃热暴露时，T1相粗化，热稳定性降低。
关键字: Al-Cu-Li合金；强度；各向异性；热稳定性；微观组织
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The relationship between microstructures and properties of a new Al-Cu-Li alloy under different aging treatments was studied by tensile test and the microstructure observation. The results show that the alloy has high strength, little anisotropy and better thermal stability. The major strengthening phases are a large number of T1 phases and part of θ′ phases in both T6 and T8 temper. Pre-deformation before artificial aging promotes the precipitation of T1 phases and obviously improves the strength of alloy. The alloy shows excellent combination of strength (σb=623.6 MPa) and ductility (δ=10.2%) when the pre-deformation ratio is controlled at about 5%. The strength of the alloy does not improve after two-stage aging, namely low-temperature aging at 120 ℃ followed by high-temperature aging at 175 ℃, but slightly enhances the ductility of alloy. In T6 and T8 temper, the anisotropy indexes (IPA) of strength are both below 5%.The alloy has excellent thermal stability at temperature below 150 ℃, but its strength decreases greatly after higher temperature (＞150 ℃)exposure due to the coarsening of T1 phases.
Key words: Al-Cu-Li alloy; strength; anisotropy; thermal stability; microstructure
