Methods for producing high purity magnesium alloys

摘要

A method for producing a high purity magnesium alloy is disclosed in which the alloying components are introduced in the molten state into molten magnesium. In accordance with the process of the invention, a predetermined amount of primary magnesium is heated and melted in a crucible. Predetermined amounts of desired alloying metals are selected and heated to their melting temperature in a separate crucible. The molten alloying metals are then introduced into the molten magnesium to substantially instantaneously alloy with the molten magnesium in a reaction raising the temperature of the melt. Elemental manganese when first alloyed with other alloying metals prior to its addition to the molten magnesium is found to consistently be more effective in reducing the iron impurity level of the melt to a level below 50 ppm. The introduction of a molten alloy of manganese and one or more rare earth metals into the molten magnesium, reduces a settling out of the rare earth metal from the melt and increases the alloying efficiency for the rare earth metal to greater than 80%. The efficiency of the process of the invention is substantially increased, the consumption of time and energy is decreased, and the production of magnesium chloride slag and gaseous HCl is avoided.