Abstract
Al-Li alloys are considered as the ideal structural materials for aerospace industry because of their low density, high specific strength and specific elastic modulus as well as low fatigue crack growth rate and good low temperature performance. 2055 AlLi alloy among new AlLi alloys developed recently is a superhigh strength Al-Li alloy. An important method to improve the performance of Al-Li alloys is to add micro-alloying elements. Er-microalloying in Al alloy has been investigated much, but the study on Al-Li alloy is still seldom reported. In this work, the effect of 0.2%Er and 0.4%Er addition on the microstructure and mechanical properties of 2055 Al-Li alloy sheet with T8 aging (6% cold rolling pre-deformation and aging at 160 °C) were investigated. The results show that the addition of 0.2% Er significantly decreases the strength by about 50 MPa, but enhances the elongation; the strength is further decreased by about 100 MPa with the addition of 0.4%Er. The precipitate types in Er micro-alloyed Al-Li alloy are not changed with the addition of Er, and the aging precipitates are still T1 (Al2CuLi) and q' (Al2Cu) phases. In the Er-microalloyed Al-Li alloy, the incubation time of T1 precipitate is longer, and its *国家高技术研究发展计划项目2013AA032401和中南大学教师基金项目2013JSJJ001资助 收到初稿日期: 2015-10-18,收到修改稿日期: 2016-01-18 作者简介:李劲风,男, 1971年生,教授,博士 DOI: 10.11900/0412.1961.2015.00537 第821-830页 pp.821-830
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