Localized corrosion behavior of the Sc microalloyed Al-Cu-Li alloy

The corrosion behavior and microstructural evolution of Sc microalloyed Al-3.2Cu-1.5Li alloys were investigated detailedly. Microstructural results demonstrated that higher levels of LAM (namely higher dislocations density) occurred in the Sc microalloyed sample, with significantly refined grains and T1 precipitates formed at a higher proportion at subgrain boundaries and dislocations. The corrosion mode of alloy is changed from intragranular corrosion to sub-intergranular and sub-intragranular corrosion after microalloying with Sc. The localized corrosion is associated with the local grain structure and distribution of T1 precipitate. Its initiation and propagation preferentially occur at the subgrain within unrecrystallized grain with high grain stored energy for Sc microalloyed samples.