Corrosion behaviour of 2A97-T8 Al-Cu-Li alloy extrusion

Highlights: • Corrosion occurs preferentially in non-recrystallized regions. • Subgrain boundaries decorated with T₁ precipitates are preferred sites for corrosion initiation. • Local corrosion susceptibility is strongly correlated to grain stored energy. • Cu-enriched layer is developed at the crevice wall of attacked grain boundaries. -- Abstract: In the present study, correlative corrosion testing and electron microscopy, including quasi-in-situ electron microscopy, are employed to investigate the corrosion behaviour of 2A97-T8 Al-Cu-Li alloy extrusion in 3.5 wt% NaCl solution. It is found that the corrosion behaviour of the alloy is influenced by synergetic effect of the plastic deformation introduced by the thermomechanical processing during alloy fabrication and the precipitation of T₁ phase during T8 treatment. Localized corrosion initiates and propagates preferentially within non-recrystallized regions of the partially recrystallized alloy. Corrosion initiated at coarse constituent intermetallic particles is confined to its periphery, which doesn't develop further when the particles are disconnected from alloy matrix.