Corrosion behavior of Mg-10Gd-2Y-0.4Zr alloy under thin electrolyte layers

Abstract

The corrosion behavior of Mg-10Gd-2Y-0.4Zr (GW102K) alloy under thin electrolyte layer (TEL) with various thicknesses was investigated by means of cathodic polarization curve, electrochemical impedance spectroscopy (EIS), and electrochemical noise (EN). Based on shot noise theory and stochastic theory, the EN results were quantitatively analyzed by using the Weibull and Gumbel distribution function, respectively. The experimental results showed that the anodic and cathodic processes of the corrosion of GW102K alloy were both retained under thin electrolyte layers. Whether under TEL or not, the cathodic process was dominated by hydrogen evolution reaction. The corrosion was more localized under thin electrolyte layer than that in bulk solution. The results also demonstrated that there were two kinds of effects for thin electrolyte layer on the corrosion behavior of GW102K alloy: (i) the rate of pit initiation was evidently retarded compared to that in bulk solution; (ii) the probability of pit growth decreased, which should be the real reason why the corrosion rate of GW102K alloy decreased with the decrease in layer thickness.