Exploring the possibility of protective surface oxides upon Mg alloy AZ31 via lutetium additions

In the present study, Mg-alloy AZ31 was alloyed with low-level lutetium (Lu) additions, with the aim of generating a more protective surface oxide/film. To stimulate Lu-rich surface films, AZ31 + Lu specimens were heat treated at 400 °C for up to 300 min. Lu was not detected in the α-Mg matrix by EDXS; instead it was incorporated in Al-Mn-Lu particles. Micro-additions of Lu promoted a significant reduction of corrosion rates of as-cast AZ31, although Lu was not detected in the surface oxide as determined by XPS. The subsequent heat treatment of as-cast AZ31 + Lu had a negative impact upon corrosion.