In this paper, mechanical properties and microstructures of the cast and extruded Al-xCu-1Li-0.4Mg–1Zn-0.1Zr alloys (x = 2.0, 3.0, 4.0, 4.5, 5.5, 6.5 wt%) were investigated. The results showed that the as-cast micrographs of alloys with different Cu content primarily consist of dendritic α-Al grains, and the intermetallic phases at the grain boundaries were Cu and Zr rich phases. After solution treatment, no recrystallization took place in extruded alloys, and the alloys mainly represented mixed textures composed of <111> and <100> fibers. Cu significantly affected the precipitation behavior of the extruded alloys. Only T₁ (Al₂CuLi) phases were observed in T6 (aging at 175 °C for 32 h) and T8 (3% pre-strain followed by aging at 150 °C for 32 h) treated alloy with 2 wt% Cu. Further increasing Cu contents (4.5 and 6.5 wt%) enabled the co-precipitation of T₁ and θ' (Al₂Cu) phases, as well as increased their density. In addition, the microstructures of grain boundaries of alloys with different Cu content showed dramatic differences. T₁ phases precipitated at the grain boundaries of alloy containing 2 wt% Cu, while rare precipitation of T₁ phases was observed at the grain boundaries of alloy with 6.5 wt% Cu. The yield strength (YS) of the alloys increased with the Cu content and the elongation (EL) showed an opposite trend. A good combination of ultra-high strength (YS = 684 MPa, ultimate tensile strength = 726 MPa) and ductility (EL = 6.3%) was obtained in T8 treated alloy containing 4.5 wt% Cu. The presence of the undesired coarse T₂ (Al₆CuLi₃) phases at the grain boundaries resulted in the premature failure of the high Cu content alloys.

在本文中，研究了铸造和挤压成型的Al- x Cu-1Li-0.4Mg-1Zn-0.1Zr合金（x  = 2.0、3.0、4.0、4.5、5.5、6.5 wt％）的力学性能和显微组织。结果表明，不同Cu含量合金的铸态显微照片主要由树枝状α-Al晶粒组成，晶界处的金属间相为富Cu和Zr相。固溶处理后，在挤压合金中没有发生再结晶，并且合金主要表现出由<111>和<100>纤维组成的混合织构。铜显着影响挤压合金的析出行为。仅T ₁（Al ₂在含2 wt％Cu的T6（在175°C下时效32 h）和T8（3％预应变，然后在150°C时效32 h）中观察到CuLi）相。进一步增加Cu含量（4.5和6.5wt％）使得T ₁和θ'（Al ₂ Cu）相能够共沉淀，并增加其密度。另外，不同Cu含量的合金晶界的显微组织表现出巨大的差异。T ₁相在含2 wt％Cu的合金的晶界处析出，而T ₁很少析出在含有6.5 wt％Cu的合金的晶界处观察到相。合金的屈服强度（YS）随铜含量的增加而增加，而伸长率（EL）则呈现相反的趋势。在含4.5 wt％Cu的T8处理合金中，获得了超高强度（YS = 684 MPa，极限抗拉强度= 726 MPa）和延展性（EL = 6.3％）的良好组合。在晶界处存在不希望的粗T ₂（Al ₆ CuLi ₃）相导致高铜含量合金的过早破坏。