热暴露对Al-Li-Cu合金力学性能和抗腐蚀性能的影响

Effects of Thermal Exposure on Mechanical Properties and Corrosion Resistance of an Al-Li-Cu Alloy

研究了Al-1.3Li-5.8Cu-0.4Mg-0.4Ag-0.12Zr合金在不同温度、不同时间下热暴露对其组织、力学性能和抗腐蚀性能的影响。合金热暴露处理后的抗拉强度随热暴露时间延长总体表现出先上升后下降的趋势;热暴露过程中,不稳定的立方相(Al5Cu6Li2)大量溶解,此时基体中大量析出细小弥散分布的T1相(Al2Cu Li),并成为基体中主要的强化相。热暴露后期,T1强化相逐渐粗化,强化效果减弱;同时,晶界无沉淀析出带不断宽化,从而导致了合金在腐蚀介质中的晶间腐蚀和剥落腐蚀敏感性增强。

The effects of thermal exposure for different time at different temperatures on microstructures, mechanical properties and corrosion resistance of A1-1.3Li-5.8Cu-0.4Mg-0.4Ag-0.12Zr alloy were investigated. It is observed that the tensile strength of three exposed samples appeared to have a decline trend after an initial ascent. During the thermal exposure, unstable cubic phase （A15Cu6Li2 ） was largely dissolved while a great amount of dispersively-distributed T1 phase （ A12 CuLl） was formed as the main strengthening phase in the matrix. In the later stage of thermal exposure, the T1 phase coarsened gradually, leading to a weakening of the strengthening effect. At the same time, the width of precipitation-free zone at grain boundaries gradually increased, resulting in an increase in the susceptibility of the alloy to inter-granular corrosion and exfoliation corrosion in corrosive medium.