Corrosion behaviour of 2A97-T6 Al-Cu-Li alloy: The influence of non-uniform precipitation

Highlights: • The distribution of T₁ phase precipitates in the Al-Cu-Li alloy is non-uniform. • Dense T₁ phase precipitate bands and precipitate-free bands exist within selected grains. • Corrosion occurs preferentially at the dense T₁ phase precipitate bands. • The selective dissolution of T₁ phase results in intragranular corrosion. - Abstract: In the present study, the influence of precipitate distribution on the corrosion behaviour of 2A97-T6 Al-Cu-Li alloy in 3.5 wt.% NaCl solution is investigated. It is found that localized plastic strain introduced to the alloy during sheet fabrication leads to the formation of dense T₁ (Al₂CuLi) phase precipitate bands and precipitate-free bands within selected grains during aging. Preferential dissolution of T₁ phase in the dense precipitate bands results in intragranular corrosion in the alloy, in the form of corrosion bands. Further, the dissolution of the alloy matrix propagates in the form of crystallographic corrosion pit.