Recycling from Mg–Al–Zn system alloy to the high-purity Mg–Zn alloy by the vacuum distillation method

Abstract

Machined chips of the Mg–Al–Zn alloy were converted to a raw material, and the recycling from Mg–Al–Zn system alloys to high-purity Mg–Zn alloys by the vacuum distillation method was examined. For 100 g of raw material AZ31 magnesium base alloy machined chips, a raw material temperature of 600°C, a condenser temperature of 355°C, and a purification time 7 h, the evaporation ratio is nearly 95%. The condenser condensate becomes about 93%, and Mg and Zn in the raw material can be almost completely recovered in the condenser as high purity Mg–Zn alloy that is free of impurities such as Fe, Ni and Cu. The corrosion rate of recycling extrusions became a little worse in comparison with about 0.5 mm/y for 4 N magnesium extrusion samples, and the corrosion resistance became better than that of AZ91D magnesium base alloy die castings. The recycling extrusions was elongated a little less in comparison with the 4 N magnesium extrusions, and the tensile strength and the 0.2% proof stress increased to about 50 MPa.