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An electrochemical study of dysprosium (III) on Bi film electrode was carried out in eutectic LiCl-KCl melts by transient and steady state electrochemical techniques. The results of transient electrochemical techniques showed that the reduction of Dy (III) appears at a more positive value than the one detected on W electrode owing to the formation of Bi-Dy intermetallic compounds through electrochemical deposition of Dy on bismuth film electrode. The thermodynamic properties of the formation for Dy-Bi intermetallics were estimated by a steady state electrochemical method in a temperature range of 713–803 K. Furthermore, the electrochemical preparation of Bi-Dy alloys was conducted by galvanostatic electrolysis at different current intensities. The Bi-Dy alloys, characterized by scanning electron microscopy equipped with energy dispersive spectrometry and X-ray diffraction, are comprised of DyBi3/5 and DyBi phases.

The work concerned the electrochemical behaviors of Y(III) on W and Ni electrodes in molten LiCl-KCl salts by a series of electrochemical techniques. The electrochemical reaction of Y(III) to Y(0) proceeded in a one-step reduction process with the exchange of three electrons, Y(III)+3e−→Y(0). Compared with the cyclic voltammogram and square wave voltammogram obtained on W electrode, the reduction potential of Y(III) on Ni electrode was observed at less negative potential than the one of Y(III) to give pure Y metal on W electrode, which revealed the occurrence of underpotential deposition of Y(III) on Ni electrode. Electromotive force (emf) measurements were performed to calculate the relative partial molar Gibbs energies and activities of Y in Y-Ni alloys. The standard Gibbs energies of formation for different Y-Ni intermetallic compounds were also estimated. The different Y-Ni alloys were formed by potentiostatic electrolysis at different potentials and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). It was found that four intermetallic compounds, YNi5, Y2Ni7, YNi3 and YNi2, were selectively produced by controlling applied potential.

The electrochemical behavior of Pr(III) and formation process of Pr-Al intermetallics were investigated by different electrochemical methods. The reduction of Pr(III) ion to metallic Pr is an one-step three-electrons reaction. The reversibility of Pr(III)/Pr(0) system was evaluated by cyclic voltammograms with different scan rates. The co-reduction of Pr(III) and Al(III) ions formed three different Pr-Al intermetallics at electrode potentials around −1.40, −1.80, and −1.95 V vs. Ag/AgCl at 723 K, respectively. Open-circuit chronopotentiometry and electromotive force (emf) measurements were carried out to estimate the relative molar Gibbs energies of Pr for the formation of different Pr-Al intermetallics in the temperature range of 723–843 K. The activities of Pr in the Pr-Al intermetallic compounds were calculated.

An electrochemical approach for the preparation of Mg-Li-Ce alloys by co-reduction of Mg, Li and Ce on a molybdenum electrode in KCl-LiCl-MgCl 2 -CeCl 3 melts at 873 K was investigated. Cyclic voltammograms (CVs) and square wave voltammograms indicated that the underpotential deposition (UPD) of cerium on pre-deposited magnesium led to the formation of Mg-Ce alloys at electrode potentials around −1.87 V. The order of electrode reactions was as follows: discharge of Mg(II) to Mg-metal, UPD of Ce on the surface of pre-deposited Mg with formation of Mg-Ce alloys, discharge of Ce(III) to Ce-metal and after that the discharge of Li + with the deposition of Mg-Li-Ce alloys, which was investigated by CVs, chronoamperometry, chronopotentiometry and open circuit chronopotentiometry. X-ray diffraction (XRD) illuminated that Mg-Li-Ce alloys with different phases were obtained via galvanostatic electrolysis by different current densities. The microstructures of Mg-Li-Ce alloys were characterized by optical microscopy (OM) and scanning electron microscopy (SEM), respectively. The analysis of energy dispersive spectrometry (EDS) showed that Ce existed at grain boundaries to restrain the grain growth. The compositions and the average grain sizes of Mg-Li-Ce alloys could be obtained controllably corresponding with the phase structures of the XRD patterns.

The electrochemical behaviour of Al, Li, and Er were investigated by electrochemical techniques, such as cyclic voltammograms, chronopotentiometric, chronoamperograms, and open circuit chronopotentiogram on molybdenum electrodes. The results showed that the underpotential deposition of erbium on pre-deposited Al electrodes formed two Al-Er intermetallic compounds. The codeposition of Al, Li, Er occurred and formed Al-Li-Er alloys in LiCl-KCl-AlCl3-Er2O3 melts at 773 K. Different phases such as Al2Er, Al2Er3 and βLi phase of Al-Li-Er alloys were prepared by galvanostatic electrolysis and characterized by X-ray diffraction (XRD). Scanning electron microscopy (SEM) indicated that Er element mainly distributed at the grain boundary. ICP analyses showed that lithium and erbium contents of Al-Li-Er alloys could be controlled by AlCl3 and Er2O3 concentration and electrochemical parameters.

An electrochemical approach for the preparation of Mg-Li-Y alloys via co-reduction of Mg, Li, and Y on a molybdenum electrode in LiCl-KCl-MgCl 2 -YCl 3 melts at 943 K was investigated. Cyclic voltammograms (CVs) illuminated that the underpotential deposition (UPD) of yttrium on pre-deposited magnesium led to the formation of a liquid Mg-Y alloy, and the succeeding underpotential deposition of lithium on pre-deposited Mg-Y led to the formation of a liquid Mg-Li-Y alloy. Chronopotentiometry measurements indicated that the order of electrode reactions was as follows: discharge of Mg(II) to Mg-metal, electroreduction of Y on the surface of Mg with formation of e-Mg 24+ x Y 5 and after that the discharge of Li + with the deposition of Mg-Li-Y alloys. X-ray diffraction (XRD) indicated that Mg-Li-Y alloys with different phases were formed via galvanostatic electrolysis. The microstructure of different phases of Mg-Li-Y alloys was characterized by optical microscope (OM) and scanning electron microscopy (SEM). The analysis results of inductively coupled plasma atomic emission spectrometer (ICP-AES) showed that the chemical compositions of Mg-Li-Y alloys corresponded with the phase structures of the XRD patterns, and the lithium and yttrium contents of Mg-Li-Y alloys depended on the concentrations of MgCl 2 and YCl 3 .

This paper presented a novel study on electrochemical codeposition of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl 2 -Yb 2 O 3 melts on molybdenum. The factors of the current efficiency were investigated. Electrolysis temperature had great influence on current efficiency; the highest current efficiency was obtained when electrolysis temperature was about 660 °C. The content of Li in Mg-Li-Yb alloys increased with the high current densities. The optimal electrolytic temperature and cathodic current density were around 660 °C and 9.3 A/cm 2 , respectively. The chemical content, phases, morphology of the alloys and the distribution of the elements were analyzed by X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry, respectively. The intermetallic of Mg-Yb was mainly distributed in the grain boundary of the alloys, presented as reticulated structures, and refined the grains. The lithium and ytterbium contents in Mg-Li-Yb alloys could be controlled by changing the concentration of MgCl 2 and Yb 2 O 3 and the electrolysis conditions.

The electrodeposition of erbium on molybdenum electrodes and the formation of Mg-Li-Er alloys were investigated in LiCl-KCl molten salts. At a molybdenum electrode, the electroreduction of Er (III) proceeded in a one-step process involving three electrons. The diffusion coefficient of erbium ions in the melts was determined by cyclic voltammetry, chronopotentiometry and chronoamperometry respectively. Cyclic voltammograms (CVs) showed that the underpotential deposition (UPD) of lithium on pre-deposited Mg-Er alloy led to the formation of a Mg-Li-Er alloy. X-ray diffraction (XRD) indicated that Er 5 Mg 24 phase was formed via potentiostatic electrolysis. Scanning electron microscopy (SEM) showed that Er atoms mainly concentrated at the grain boundaries while Mg element evenly located in the alloy.

The electrochemical preparaton of Al-Li-Y alloys from LiCl-KCl-AlCl3-Y2O3 system was studied. The chlorination of Y2O3 by AlCl3 led to the formation of Y (III) ions in the molten salts. Cyclic voltammogram (CV) showed that the underpotential deposition (UPD) of yttrium on pre-deposited aluminum caused the formation of Al-Y alloy. Al-Li-Y alloys with different yttrium contents were obtained by galvanostatic electrolysis and analysed by SEM-EDS and ICP. The ICP results showed that the lithium and yttrium contents in Al-Li-Y alloys depended on the addition of AlCl3 into the melts.

Different phases of Mg-Li-Sm alloys were prepared by galvanostatic electrolysis in LiCl-KCl-MgCl 2 -SmCl 3 melts at 670 °C. The electrolysis process and phase control of Mg-Li-Sm alloys were studied. The microstructures of α, α+β, β phases of Mg-Li-Sm alloys were characterized by X-ray diffraction (XRD) and optical microscope (OM). Analysis of scanning electron microscopy (SEM) and EDS mapping analysis showed that Mg distributed homogeneously in Mg-Li-Sm alloys. EDS result showed that the distribution of Sm was more at grain boundaries than within the grains. Inductively coupled plasma (ICP) analyses of the samples obtained by electrolysis showed that the chemical compositions of Mg-Li-Sm alloys were consistent with the phase structures of XRD patterns, and the lithium and samarium contents in Mg-Li-Sm alloys could be controlled by the electrolysis time and concentrations of SmCl 3 . Effect of Sm on corrosion property of Mg-12Li alloy was studied. The corrosion resistance of the alloy improved firstly and then worsened with the increase of Sm content. The optimum Sm content was about 0.7 wt.%.

The electrochemical behavior of Yb3+ and electrodeposition of Mg-Yb alloy film at solid magnesium cathode in the molten LiCl-KCl-YbCl3 (2 wt.%) system at 773 K was investigated. Transient electrochemical techniques, such as cyclic voltammetry, chronopotentiometry and chronoamperometry were used in order to explore the deposition mechanism of Yb. The reduction process of Yb3+ is stepwise reactions which are single-electron and double-electron reversible charge transfer reactions. The speed control step was a diffusion-controlled step which is caused by concentration polarization. The microstructures of Mg-Yb alloy film were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and EPMA area analysis. A very thin Mg2Yb alloy film (∼200 nm) was formed by potentiostatic electrolysis at −1.85 V (vs. Ag/AgCl) for 12 h. A much thicker Mg2Yb alloy film (∼450 μm) was obtained at −2.50 V (vs. Ag/AgCl) for 2.5 h. The corrosion resistance of magnesium can be enhanced by electrochemical formation of Mg-Yb alloy film on its surface.

Electrocodeposition of Mg-Li-Sm alloys was investigated in molten KCl-LiCl-MgCl 2 -SmCl 3 -KF system. The effects of electrolytic temperature and cathodic current density on current efficiency were studied and optimal electrolysis parameters were obtained. The optimum electrolysis condition was a molten salt mixture of LiCl: KCl =50:50 (wt.%), electrolytic temperature: 660 °C, cathode current density: 9.5 A/cm 2 and electrolysis time of 40 min. The current efficiency reached 77.3%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses of the deposits indicated that Mg-Li-Sm alloys, having Mg, βLi and Mg 41 Sm 5 phases, were obtained by electrocodeposition in molten system. The content and distribution of elements in Mg-Li-Sm alloys were analyzed by ICP-MS and EPMA, respectively. The results showed that the distribution of Mg and Sm was homogeneous in the alloys. ICP analyses of samples obtained by electrolysis showed that lithium contents in Mg-Li-Sm alloys could be controlled by MgCl 2 concentration and electrochemical parameters. It was proved that preparation of Mg-Li-Sm alloys by electrocodeposition in molten salt was feasible.