Electrochemical Behavior of Magnetron-Sputtered Al–Cu Alloy Films in Sulfate Solutions

Model alloys, generated by magnetron sputtering, have been employed to understand the role of copper on the corrosion behavior of aluminum alloys. Binary Al-Cu alloys, with copper contents between 0 and 100 atom %, were synthesized with well-controlled compositions, embracing single-phase alpha and theta alloys together with multiphase alloys. Electrochemical measurements confirmed the stability of the thin alloy films and revealed that the corrosion behavior of the alpha, theta, and eta2 phases differed strongly in the cathodic region. Further, in the anodic region, phases of high copper content suffered pitting in sulfate solutions, while the alpha phase remained passive.