Surface and interface investigation of electrochemically induced corrosion on a quaternary bronze

A quaternary (Cu-Zn-Sn-Pb) cast bronze was submitted to an electrochemical corrosion experiment using an anodic polarization sweep. The surface/interface chemical analysis of the patina removed after the anodic polarization and the metallographic observations on the corroded bulk alloy highlight the onset of a dezincification process followed by a decuprification process, aswell as the formation of a Sn-enriched layer located at the interface patina-bulk alloy. Different local corrosion patterns, as CuCl precipitation in pits, epitaxial growth of corrosion products on dendritic structures and of Cl-enriched oxyhydroxides, are observed too. The results are discussed in comparison with experimental findings obtained in previous ageing tests performed on the same alloy in different chloride-containing solutions