Purification technology of AZ91 magnesium alloy wastes

The effects of different purification processes on the mechanical properties, structure and fracture pattern of AZ91 magnesium alloy wastes were studied. The results show that the inclusions in the Mg melt can be removed effectively by the treatment of the fluxes with MgO foam ceramic filter. Therefore, the properties of magnesium alloy wastes can be improved substantially. Tensile strength and elongation of the magnesium alloy wastes after purification treatment can reach 194.6 MPa and 5.12% respectively, which are comparable to the mechanical properties of AZ91 fresh stuff. The metallographic analysis results show that the purification treatment has not obvious effect on metallurgical structure. The fracture mechanism of AZ91 is not changed, and its fractures are still quasi-cleavage crack. It is discovered that for AZ91 magnesium alloy, the fluxes containing TiO2 can decrease the Fe content of magnesium alloy wastes to below 0.0056%. The results also show that TiO2 is helpful for the precipitation of γ phase in granular or small island shape and can refine the grain size effectively.