Microalloying to Inhibit Oxidation of Al–Mg Alloys

The oxidation of liquid Al–Mg alloys during holding and casting can lead to issues resulting in poor metal quality and increased dross formation and melt loss. Historically, beryllium as a microalloying element has been used to inhibit the oxidation of high Mg alloys. Due to the negative health consequences, an alternative is desired for beryllium. Potential alternative microalloying elements to Be were investigated in gram and kg-scale TGAs. The effects of Ca, Ce, Ga, Gd, La, Sc, and Sr on the oxidation of a 5% Mg alloy were investigated in a gram-scale TGA. Additions of Ce, Ga, Gd, La, and Sc were found to have no measurable inhibiting effect on the oxidation with additions up to 1000 ppm. Ca and Sr showed a potential inhibiting effect and were investigated therefore further in a self-made kg-scale TGA. Sufficient concentrations of Ca or Sr inhibited the transformation from MgO to MgAl2O4 and could be a future replacement for Be.