Effect of rotating gas bubble stirring process parameters on purifying effectiveness and mechanical properties of sand-cast Mg–10Gd–3Y–0.5Zr alloy

A continuous nonflux inclusion-removal method, rotating gas bubble stirring, is used to purify Mg–10Gd–3Y–0.5Zr melt. The effects of rotating gas bubble stirring process parameters (Ar flow rate, time, and rotating speed) on purifying effectiveness, mechanical properties, and fracture behavior of sand-cast Mg–10Gd–3Y–0.5Zr alloy are studied. The results show that too high or too low Ar flow rate is unfavorable for inclusion-removal. The results also indicate that the high rotary speed of spraying gas is helpful to improve the inclusion-removal and mechanical properties. But when the melt is subjected to overtime gas bubbling treatment, the mechanical properties became poor again. Nonflux purification does not change the microstructure of Mg–10Gd–3Y–0.5Zr alloy. However, rotating gas bubble stirring has a certain effect on the fracture pattern of the alloy. In addition, the melt purifying mechanism of the gas bubble stirring treatment for the sand-cast alloy was discussed systematically.