Crystallographic defects induced localised corrosion in AA2099-T8 aluminium alloy

Abstract

A correlation has been revealed between the localised corrosion susceptibility and the grain stored energy in AA2099-T8 aluminium alloy, with grains of higher stored energy being relatively more susceptible to corrosion attack. The grains of high stored energy contain increased crystallographic defects, which could consequently decrease their corrosion resistance. Additionally, since crystallographic defects are preferential sites for the precipitation of T1 (Al2CuLi) phase, it is suggested that grains of high stored energy could also contain increased volume fraction of T1 phase after aging, which might further increase corrosion susceptibility due to the electrochemically high activity of lithium rich T1 phase.