The Corrosion Behavior of As-cast Mg–4Al–xEr–0.3Mn Alloys

Magnesium and magnesium alloys are light-weighting candidates as the structure materials. The microstructure and corrosion behavior of Mg–4Al–xEr–0.3Mn (x = 2, 4, 6 all in wt%) alloys were studied. The results showed that the morphology, size and distribution of Mg17Al12 phase were gradually improved with the increasing of Er content, and a large number of Al2Er were observed. The Al2Er inhibited the hydrogen evolution reaction and promoted the growth of passivation film. Er oxides or hydroxides were found on the surface of the passivation film, and the charge transfer resistance of the film was 4447Ωcm2, while the film resistance was 5852Ωcm2, which reduced the electron transfer efficiency and improved the density and stability of the passivation film, thus greatly improving the corrosion resistance. As Er content reaches 6wt%, the corrosion rate decreases by nearly 45%. © The Author(s) 2021.