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 Eκ 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.