The electrochemical behaviour of the Al2Cu intermetallic compound

The aim of this work was to give an extensive electrochemical description of the Al2Cu compound and explain the reported discrepancies. Stationary potentiodynamic polarization on static electrodes and rotating ring disc-electrodes and potentiodynamic polarization were carried out on an Al2Cu compound in sulphate solutions of different Ph values. Al2Cu under self corrosion conditions as well as under anodic polarization conditions dissolves with the formation of aluminium and copper ions. The latter are reduced on the electrode in the range of potentials corresponding to stability of metallic copper. The current maximum of the anodic curve, whose shape is characteristic for a transition from an active to passive state, represents, in this case, the maximum rate of copper dissolution from the electrode surface. For higher potential values the existence of a passive state is possible at the stability of aluminium hydroxide, copper hydroxide or of both hydroxides, depending on the potential value and on the Ph value of electrolytes.