Method for preparing aluminum-magnesium-scandium intermediate alloy by using aluminum-magnesium thermal reduction method in sodium fluoride-sodium chloride-potassium chloride molten salt system

The invention discloses a method for preparing an aluminum-magnesium-scandium intermediate alloy by an aluminum-magnesium thermal reduction method in a sodium fluoride-sodium chloride-potassium chloride molten salt system. According to the method, scandium fluoride serves as a raw material, NaF, NaCl and KCl serve as a molten salt system, magnesium metal serves as a reducing agent, and the aluminum-magnesium-scandium intermediate alloy is prepared through an aluminum-magnesium thermal reduction method under the non-vacuum condition, and the method comprises the following steps that firstly, NaF, NaCl and KCl are mixed according to a certain mass ratio, ground and dried to prepare mixed salt; (2) putting an aluminum ingot and a magnesium ingot into a high-purity graphite crucible until the aluminum ingot and the magnesium ingot are completely molten, and then adding mixed salt in proportion until the mixed salt is completely molten; and (3) adding scandium fluoride in multiple batches, controlling the temperat