Electrochemical behaviour and corrosion of Mg–Y alloys

Corrosion of cast magnesium–yttrium (Y) alloys with systematic Y additions up to a nominal 18 wt.% were studied. Corrosion performance was related to the quantitative alloy microstructure and found to increase significantly with the level of alloying and volume fraction of the Mg–Y intermetallic present. In the alloy microstructures, Mg24Y5 was principally formed; the electrochemistry of which was characterised using the electrochemical microcell method. Electrochemical testing revealed the fundamental corrosion behaviour of Mg–Y alloys and elucidated the corrosion mechanisms at play.

► The corrosion performance of Mg–Y alloys reported over the largest compositional range to date. ► Quantitative microscopy identified the Mg–Y intermetallic that formed. ► Quantification of intermetallic electrochemistry via the microcell technique. ► A rational description of the corrosion response for Mg–Y alloys based on kinetics is given.