Anomalous hydrogen evolution on AZ31, AZ61 and AZ91 magnesium alloys in unbuffered sodium chloride solution

By Fajardo, S.; Bosch, J.; Frankel, G. S.
Published in Corrosion Science 2019

Abstract

The anomalous hydrogen evolution (HE) exhibited by the Mg alloys AZ31, AZ61 and AZ91 was studied in unbuffered 0.1 M NaCl solution using electrochemical testing and gravimetric hydrogen collection. Strong anomalous HE was observed for all three alloys, but the rate decreased with increasing content of Al. The cathodic potentiodynamic response and surface appearance of the different alloys showed that the corrosion products were not responsible for the anomalous HE. Assessment of the charge transfer coefficients for the Mg dissolution and HE reactions supported the previously-proposed kinetic model describing how anomalous HE originates at the actively dissolving Mg regions.

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