Abstract:A new flux which can remove both Fe and non-metallic inclusions in magnesium alloy was introduced. The Fe content of the magnesium alloy can be decreased greatly from 0.062% to lower than 0.005% (degree of AZ91D) after being purified by this new flux. The optimum addition of B2O3in the flux is 0.58 % by Gaussian Curve Fitting. Corrosion rate was measured after the specimen being immersed in 5% NaCl solution for 3 d. The results show that the corro-
sion rate of the magnesium alloy after purification by the new flux is only 0.3 mg·cm^-2·d^-1. On the other hand, nonmetallic inclusions in the magnesium alloy decrease with increasing addition of JDMJ in the new flux. Average volume fraction of the non-metallic inclusions in the magnesium alloy decreases from 1.52% to 1.08%, which leads to improvement in the mechanical properties of the magnesium alloy by 30%. The mechanisms of Fe reduction and non-metallic in clusion-removing in magnesium melt by purification with the new flux were also revealed.

Key words: magnesium alloy; flux; purification; Fe; non-metallic inclusion