Rare earth can simultaneously enhance mechanical properties and corrosion resistance of Al-Mg-Mn alloys. Among them, yttrium (Y) possesses the advantages of lower cost and high crust abundance. Effect of Y content (0.1, 0.2, 0.3 wt.%) on microstructure and corrosion resistance of as-cast Al-Mg-Mn alloys was examined. With increasing Y content, the number of Al 3 Mg 2 and Al 6 (Fe, Mn) is gradually decreased, and the number of Y-containing precipitates is increased. After 0.3 wt.% Y addition, Al 6 (Fe, Mn) disappears and the Y-containing phases dominate. Galvanic corrosion is reduced since the potential difference between the α-Al and Y-containing phases is lower than that of the Al 6 (Fe, Mn) phase. Furthermore, after Y addition, volume fraction of Al 3 Mg 2 is reduced, which improves intergranular corrosion resistance.
Tang et al. (Tue,) studied this question.