Electrical conductivity of molten LiF–DyF₃–Dy₂O₃–Cu₂O system for Dy–Cu intermediate alloy production

Abstract

Dy–Cu intermediate alloys have shown substantial potential in the field of magnetostrictive and magnetic refrigerant materials. Therefore, this study focused on investigating the electrical conductivity of molten-salt systems for the preparation of Dy–Cu alloys and on optimizing the corresponding operating parameters. The electrical conductivity of molten LiF–DyF₃–Dy₂O₃–Cu₂O systems was measured from 910 to 1030°C using the continuously varying cell constant method. The dependencies of the LiF–DyF₃–Dy₂O₃–Cu₂O system conductivity on the melt composition and temperature were examined herein. The optimal operating conditions for Dy–Cu alloy production were determined via analyses of the electrical conductivity and activation energies for conductance, which were calculated using the Arrhenius equation. The conductivity of the molten system regularly increases with increasing temperature and decreases with increasing concentration of Dy₂O₃ or Cu₂O or both. The activation energy E_κ of the LiF–DyF₃–Dy₂O₃ and LiF–DyF₃–Cu₂O molten-salt systems increases with increasing Dy₂O₃ or Cu₂O content. The regression functions of conductance as a function of temperature (t) and the addition of Dy₂O₃ (W(Dy₂O₃)) and Cu₂O (W(Cu₂O)) can be expressed as κ = −2.08435 + 0.0068t − 0.18929W(Dy₂O₃) −0.07918W(Cu₂O). The optimal electrolysis conditions for preparing the Dy–Cu alloy in LiF–DyF₃–Dy₂O₃–Cu₂O molten salt are determined to be 2.0wt% > W(Dy₂O₃) + W(Cu₂O) > 3.0wt% and W(Dy₂O₃): W(Cu₂O) = 1:2 at 970 to 1000 °C.