The Electrochemical Behavior of Al‐Ga Alloys in Alkaline and Neutral Electrolytes

Abstract

The electrochemical behavior of a range of Al‐Ga alloys was determined in and both under normal polarization conditions and in a small battery designed for viewing reacted anodes in a scanning electron microscope. The observed behavior was compared with that of gallium and Ga‐0.1% Al. It was found that the electrochemistry of Al‐Ga was controlled by that of gallium in as much as Al‐Ga alloys with low levels of gallium could only display active behavior in alkali if initially polarized below the reduction voltage. The activation phenomenon took place at localized surface sites associated with gallium agglomerates, a likely mechanism being rapid diffusion of aluminum through the gallium particles which seemed to prevent the normal, passive behavior of aluminum. The speed of activation after current switch‐on varied inversely with alloy gallium concentration and depended on a critical surface concentration of gallium being achieved. Back‐diffusion of gallium away from the surface strongly influenced the activating capabilities of alloys with lower levels of gallium. Cooling of activated Al‐Ga alloys resulted in deactivation caused by surface gallium solidification and passivation.