Microstructural origin of localized corrosion in anodized AA2099‐T8 aluminium–lithium alloy

The microstructural origin of localized corrosion in AA2099‐T8 aluminium–lithium alloy after tartaric‐sulfuric acid anodizing and sulfuric acid anodizing has been investigated. It is suggested that the high‐copper‐containing constituent Al–Fe–Mn–Cu particles are responsible for the initiation of localized corrosion in the anodized alloy. Once the anodic film at the defects associated with the high‐copper‐containing particles has been penetrated by the corrosive media, localized corrosion may further propagate in the alloy substrate, and the propagation is controlled by the alloy microstructure immediately beneath the anodic film at the initiation site.