Localized corrosion inhibition by cerium species on clad AA2024 aluminium alloy investigated by means of electrochemical micro-cell

AA2024 clad with AA1050 was immersed in CeCl3 solutions under aerated and O2 saturated conditions to promote the deposition of cerium species. The Ce deposition occurs on the entire sample surface. The amount of Ce detected on the intermetallics is larger than on the matrix. The deposition is activated by alkaline etch of the substrate. The breakdown potential in potentiodynamic polarization curves becomes more positive due to the Ce deposition both on the areas containing Fe-rich intermetallics and on the matrix. Characterization by micro-cell indicates that the overall electrochemical behaviour is improved by the Ce deposition.

► Alkaline etch of the substrate enhances precipitation of Ce compounds.
► The deposition of Ce species occurs on the entire sample surface.
► The amount of Ce detected on the intermetallics is larger than on the matrix.
► The breakdown potential of areas containing intermetallics and the matrix becomes more positive due to Ce deposition.