Preparation process of magnesium alloys by complex salt dehydration-electrochemical codeposition

High-purity anhydrous MgCl₂-containing molten salt was directly synthesized from MgCl₂ · 6H₂O via complex salts dehydration and protection. After that, Mg-Al and Mg-Zn alloys were prepared by electrochemical codeposition. The hydrolysis processes of magnesium chloride hexahydrate in various chloride mixtures were studied. Then, the preparation process was studied and the dehydration mechanism was put forward. NH₄Cl·MgCl₂·nH₂O formed under 300°C inhibits the formation of hydrolysate during the dehydration process. KMgCl₃ and K₃NaMgCl₆ formed above 400°C can further protect the unstable anhydrous MgCl₂. Therefore, high-purity anhydrous MgCl₂-containing molten salt with w(MgO)/w(MgCl₂) being 0.016 wt.% was obtained. The current efficiency was above 81% and 97%, respectively, when preparing Mg-Al alloys and Mg-Zn alloys, and the alloying elements were distributed homogeneously in the alloy matrix.