The Preparation Of Ce(Y)-Ni And Mg-Li-Ce-Y Alloys In Molten Salts

The electrochemical behaviors of Ce(III) and Y(III) ions on inert W electrode and formation of Ce-Ni and Y-Ni on reactive Ni electrode were researched in LiCl-KCl molten salts. The Ce-Ni and Y-Ni intermetallic compounds were obtained by potentiostatic electrolysis. The electrochemical behaviors of LiCl-KCl melts after the addition of MgC12,CeCl3 and YCl3 were salso explored. The Mg-Li-Ce-Y alloys were prapared by galvanostatic electrolysis and characterized by XRD, SEM-EDS and ICP-AES.(1) The electrochemical behaviors of Ce(?) ions was researched on inert W and reactive Ni electrodes in LiCl-KCl molten salts at 873 K. The electrochemical reduction of Ce(?) ions to Ce(0) was determined to exchange three electrons in one step. When the scan rate was less than 200 mV/s-1, the reduction of Ce(?) ions was reversible process and controlled by mass transfer.According to different scan rate of cyclic voltammetry and chronopotentiometry, diffusion coefficient of Ce(?) was calculated to be about 4.0�10-5 cm2/s. The Ce-Ni intermetallic compound was obtained by potentiostatic electrolysis. The Ce-Ni intermetallic compounds(CeNi2,CeNi3, Ce7Ni3) were analyzed by XRD and SEM-EDS,respectively. The Gibbs energies of formation for CeNi2?CeNi3 and Ce7Ni3 were calculated by open circuit chronopotentiometry.(2) The electrochemical behavior of Y(?) ions was researched on inert W and reactive Ni electrodes in LiCl-KCl molten salts at 873 K. The electrochemical reduction of Y(?) ions to Y(0)proceed in one-step with three electrons exchanged. When the scan rate was less than 200 mV/s,the reduction of Y(?) ions was quasi-reversible process and controlled by mass transfer. The diffusion coefficient of Y(?) was found to be about 2.O�10-5 cm2/s. The Y-Ni intermetallic compounds were obtained by potentiostatic electrolysis at -1.5, -1.7 and -1.9 V, respectively. The Y-Ni intermetallic compounds were analyzed by XRD and SEM-EDS. The thermodynamic properties of YNi5? YNi3 and YNi2 were calculated by open circuit chronopotentiometry.(3) The electrochemical behaviours of Ce(?) and Y(?) ions were researched on inert W electrodes in LiCl-KCl-MgCl2 molten salts at 873 K. It was found that the Ce(?), Y(?) and Mg(?) could be codeposition, while cathode current density was higher than -0.32 A/cm2 or cathode potential was more negative than -2.35 V. The formation of Mg-Li-Ce-Y alloys were conducted and the effect of electrolytic time, electrolytic temperature and current density on the current efficiency and alloy composition were studied. The current efficiency could reach 70%When the electrolytic temperature was 973 K, electrolytic time was 3 h and cathode current intensity was between -1.5 and -2.0 A. The content of MgCl2 was the main influence factors on the content of Li and Re in Mg-Li-Ce-Y alloys. If the concentration of MgCl2 was reduced, the content of Li and Re in alloys could be increase. According to the results of XRD and SEM-EDS,Mg, Mg3Ce and Mg2Y were found in alloy samples. And element Ce and Y were uniform distribute in grain boundary of alloys.