A Review on the Semiconducting Behavior of Passive Films Formed on Mg Alloys by Mott-Schottky Analysis

Mg alloys have a vast usage where weight reduction is really significant since they do the features really well for materials of ultra-light weight. However, Mg is inherently a reactive metal and its alloys generally possess quite weak corrosion resistance that widely restricts their technological usages, especially in some rough service conditions. Despite, many investigations on the passive and electrochemical properties of Mg alloys and their relation with the microstructure of these alloys, few reports have been devoted to investigate the semiconducting behavior of the formed oxide layers on these alloys. Mott-Schottky measurement is a major in-situ technique to analyze semiconductor behavior of passive layers. In this review, the semiconducting properties of formed passive layers on Mg alloys (AZ91D, AZ31B, AZ80, Mg-Y-Rare Earth-Zr alloys) by Mott-Schottky measurement has been assessed. Mott-Schottky measurements revealed the formed passive films on Mg alloys show mainly n-type behavior regardless the microstructure, pH, immersion time, and temperature of electrolyte.