The effects of aging treatment on the high temperature mechanical properties of cast Al–2Li–2Cu-0.5Mg-0.15Sc-0.15Zr-0.05Ti alloy were investigated. Different test temperature (25 °C, 175 °C, 200 °C, 225 °C) and aging time (aging for 8 h, 32 h, 64 h at 175 °C) were designed for comparison. The results showed that at room temperature, the strength of the alloy improved with the prolongation of aging time. When the test temperature increased from 175 °C to 225 °C, the δ′(AlLi)-Precipitation Free Zone (δ′-PFZ) widened from 31.25 nm to 110.83 nm, causing a decrease in strength. In addition, the presence of the dynamic recrystallization at 225 °C resulted in an increase in elongation. As the aging time prolonged from 8 h to 64 h, the high temperature strength of the alloy at 225 °C decreased first and then enhanced. The improvement of alloy strength aged for 64 h was mainly due to the increase of T(AlCuLi), S′(AlCuMg) phases and the decrease of δ′(AlLi) phases. The alloy aged for 64 h exhibiting excellent high-temperature performance at 225 °C, which the yield strength reached 302 MPa, the tensile strength reached 312 MPa and the elongation reached 4.4%. The results indicated that δ′-PFZ widening, precipitation strengthening and dynamic recrystallization were the main factors which influenced the high temperature mechanical properties of Al–Li–Cu alloy.

中文翻译：

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时效处理对铸造Al-Li-Cu合金高温力学性能的影响

研究了时效处理对铸造Al-2Li-2Cu-0.5Mg-0.15Sc-0.15Zr-0.05Ti合金高温力学性能的影响。设计了不同的测试温度（25℃、175℃、200℃、225℃）和老化时间（175℃老化8小时、32小时、64小时）进行比较。结果表明，在室温下，合金的强度随着时效时间的延长而提高。当试验温度从175℃升高到225℃时，δ′(AlLi)-无沉淀区(δ′-PFZ)从31.25 nm变宽到110.83 nm，导致强度下降。此外，225°C 下动态重结晶的存在导致伸长率增加。随着时效时间从8 h延长至64 h，合金在225 ℃的高温强度先下降后增强。时效64 h合金强度的提高主要是由于T(AlCuLi)、S'(AlCuMg)相的增加和δ'(AlLi)相的减少。该合金在225 ℃时效64 h后表现出优异的高温性能，屈服强度达到302 MPa，拉伸强度达到312 MPa，延伸率达到4.4%。结果表明，δ′-PFZ展宽、沉淀强化和动态再结晶是影响Al-Li-Cu合金高温力学性能的主要因素。