Electrochemical Formation of Dy-Fe and Nd-Fe Alloys in Molten CaCl₂-LiCl Systems

Here we study the recovery process of rare earth metals from Nd magnet scraps via electrolysis in a molten salt and with an alloy diaphragm. In the present study, the electrochemical formation of Dy-Fe and Nd-Fe alloys, which was an important step of the recovery process, was investigated in molten CaCl₂-LiCl systems at 873 K. Two Dy-Fe alloy samples were prepared by potentiostatic electrolysis of Fe plate electrodes at 0.30 V (vs. Li⁺/Li) and 0.50 V for 1 h in CaCl₂-LiCl-DyCl₃ (0.50 mol% added). The formation of DyFe₅ was suggested by X-ray diffraction (XRD). Potentiostatic electrolysis was also conducted at 0.30 V and 0.50 V for 1 h using Fe plate electrodes in CaCl₂-LiCl-NdCl₃ (0.50 mol% added). XRD analysis suggested the formation of Nd₂Fe₁₇ for both samples. The equilibrium potentials for (DyFe₅+Fe) and (Nd₂Fe₁₇+Fe) coexisting phases were indicated.