Influence of heat treatments and Ca additions on the passivation behaviour of high‐pressure die cast AM50

The influence of heat treatments and Ca additions on the corrosion behaviour of HPDC AM50 was studied using potentiodynamic polarisation technique in bi‐distilled water at pH=8. Heat treatments caused a considerable modification of the polarisation behaviour, which manifested itself in a wide range of passivity in the anodic branch. During heat treatments, the Mg solid solution was enriched from 2 wt.% to 4 wt.% Al due to the partial dissolution of the β‐phase. This enabled the comprehensive formation of a double‐structured passive layer during polarisation. Only minor effect of Ca additions (0.7 wt.%) on the corrosion behaviour of AM50 was observed.