Using EIS to analyse samples of Al–Mg alloy AA5083 treated by thermal activation in cerium salt baths

This paper describes a study undertaken of the morphological and anticorrosive characteristics of surface layers formed on the Al–Mg alloy AA5083 from solutions of Ce(III), by means of various heat treatments while immersed in baths of cerium salts. SEM/EDS studies have demonstrated the existence of a heterogeneous layer formed by a film of aluminium oxide/hydroxide on the matrix and a series of dispersed islands of cerium deposited on the cathodic intermetallics. With the object of evaluating the degree of protection provided by the layers formed and of characterising the particular contribution of the electrochemical response of the system in NaCl, the results obtained by means of EIS are presented and discussed.