Formation and Phase Control of Dy Alloy Films by Electrochemical Implantation and Displantation

The electrochemical formation of Dy-Ni alloys was studied in a molten (0.50 mol %) system at 700 K. Potentiostatic electrolysis of a Ni electrode at 0.55 ( vs. 0.62, and 0.70 V for 2 h resulted in formations of the coherent and minute films having thickness of about 60, 30, and 20 μm, respectively. The growth rates of the films were extremely high, when considering conventional solid phase diffusion. Moreover, the growth rate was dependent on the applied potentials, i.e. , higher at more negative potentials. Thus, the formation was regarded as a kind of electrochemical implantation, which was found by the authors previously. The formed electrodes could be transformed to other phases, i.e. , and Ni, by electrochemical displantation. The several transformation reactions and the corresponding equilibrium potential were clarified. The minute films were changed to porous films at more positive potentials during the transformation reaction.