AN ELECTROCHEMICAL INVESTIGATION OF THE BEHAVIOR OF ALUMINUM-ALLOYS IN DIFFERENT ELECTROLYTES

The anodic behaviour of aluminum alloys, mainly Al 5083-H321 and Al 6061-T651, in aqueous chloride solution in the presence of sulphate ions has been investigated at room temperature by the linear sweep polarization technique and potential step method. For both electrodes the i-E curves were characterized by a minor peak prior to the major dissolution region, but with the high current density for Al 5083-H321 due probably to a monolayer(s) formation of Al2O3 and/or MgO. The detection of Mg was shown by SIMS analyses. Significant pitting was observed for Al 5083-H321, as a result of the combined effects of the electrochemically active Mg in the matrix of the electrode, its subsequent influence on hydrogen evolution, and the chloride attack on the aluminum electrode surface. © 1990.