Electrochemical Formation of Pr–Ni Alloys in LiF–CaF₂–PrF₃and NaCl–KCl–PrCl₃Melts

For the establishment of a process for the electrochemical recovery of rare earth elements from used magnet scraps, the electrochemical formation of Pr–Ni alloys in molten LiF–CaF 2 –PrF 3 and NaCl–KCl–PrCl 3 salts at 1123 K and 973 K, respectively, was investigated. Cyclic voltammetry and open-circuit potentiometry indicated the formation of several phases of Pr–Ni alloys. Alloy samples were prepared by one- or two-step potentiostatic electrolysis using a Ni plate electrode at various potentials. Scanning electron microscopy observations and X-ray diffraction measurements confirmed the formation of PrNi 2 , PrNi 3 , Pr 2 Ni 7 , and PrNi 5 . The formation potential for each Pr–Ni alloy phase was determined from experimental results. In addition, the optimum electrolysis conditions for the separation of Nd, Dy, and Pr are discussed.