Electrochemical behaviour of binary Al-Ga and ternary Al-Zn-Ga alloys as function of thermodynamic properties

Abstract

The present work underlines the influence of phase transformations on the electrochemical behaviour of Al-Ga binary alloys and Al-Zn-Ga ternary alloys used as sacrificial anodes. A study of the Al-Zn-Ga ternary phase diagram was conducted to find stable and metastable equilibria. Knowledge of these equilibria permitted the definition of the thermal treatments which govern, at room temperature, the existence (or otherwise) of a gallium rich liquid phase in the alloys. More significant depassivation was observed when the thermodynamic data indicated that gallium was in the liquid state. For these alloys, a correlation between electrochemical depassivation and the phase diagram was established.