Abstract The influence of Zn addition on microstructure evolution and mechanical performance of a novel cast Al-Li-Cu-Mg alloy is studied in detail. The results reveal that Zn modifies the precipitation behaviors and improves the tensile strength effectively. As Zn content increases to 1 wt%, the precipitation of T1 (Al2CuLi) phase is greatly enhanced at the expense of S′ (Al2CuMg) phase. Zn atoms are observed to enrich in T1 phase by using high-angle annular dark field-scanning transmission electron microscope (HADDF-STEM), possibly attributed to some Cu atoms being substituted by Zn atoms. The precipitation of δ′ (Al3Li) is increased as Zn addition, suppressing the widening of δ′-precipitation-free zones. A more uniformly distribution of S'is also observed in the Zn-containing alloys. With the collaborative effect of both T1 and δ′ precipitates, the optimal ultimate tensile strength of 504 MPa is obtained in 1 wt% Zn-containing alloy aged at 175 °C for 64 h, which is the highest value in cast Al-Li alloy field at present.

中文翻译：

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Zn对高强度铸造Al-Li-Cu合金析出析出及力学性能的影响

摘要 详细研究了Zn添加对新型铸造Al-Li-Cu-Mg合金组织演变和力学性能的影响。结果表明，Zn 改变了析出行为，有效地提高了拉伸强度。随着 Zn 含量增加到 1 wt%，以 S' (Al2CuMg) 相为代价，T1 (Al2CuLi) 相的析出大大增强。通过使用高角度环形暗场扫描透射电子显微镜（HADDF-STEM）观察到 Zn 原子在 T1 相中富集，这可能归因于一些 Cu 原子被 Zn 原子取代。随着Zn的加入，δ'（Al3Li）的析出增加，抑制了无δ'析出区的扩大。在含锌合金中也观察到了更均匀的 S' 分布。