Improved corrosion resistance of 2195 Al-Cu-Li alloy through T6I6 interrupted aging

An interrupted aging treatment, T6I6, was conducted on 2195 Al-Cu-Li alloy to improve the corrosion re-sistance. The microstructure evolution, intergranular corrosion (IGC), exfoliation corrosion (EXCO), and electrochemical corrosion behaviors of 2195 Al-Cu-Li alloy subjected to T6I6 and T6 aging treatment were systematically investigated. The results reveal that the number density of T1 (Al2CuLi) phases in the grain interior and at the grain boundaries of T6I6 sample increases by suppressing the precipitation of theta' (Al2Cu) phases. The higher density of T1 phases along the grain boundary can increase the potential difference between the grain boundary precipitates (GBPs) and Al matrix, resulting in decreased corrosion resistance. However, the GBPs coarsening and precipitate free zone (PFZ) narrowing induced by interrupted aging offset the harmful effects of T1 phases, which are responsible for the improved corrosion resistance of T6I6 sample. Hence, the proposed T6I6 aging treatment more effectively improves the corrosion resistance for the studied alloy compared to T6 aging. (c) 2023 Elsevier B.V. All rights reserved.