Direct Electrodeposition of Quarternary Mg–Li–Al–Zn Alloys from Their Chloride Melts

Abstract

Direct electrodeposition of quarternary Mg–Li–Al–Zn alloys on a molybdenum electrode from LiCl–KCl–MgCl2–AlCl3–ZnCl2 melts at 943 K was investigated. Cyclic voltammograms (CVs) showed that the deposition potential of Mg shifts in a positive direction after adding AlCl3 and ZnCl2. Chronopotentiometry measurements indicated that the codepositon of Mg, Li, Al, and Zn occurs at current densities lower than −0.47 A cm−2. X-ray diffraction (XRD) indicated that Mg–Li–Al–Zn alloys with different phases were prepared via galvanostatic electrolysis. The microstructures of typical α + β and β phases of Mg–Li–Al–Zn alloys were characterized by optical microscope (OM) and scanning electron microscopy (SEM). The analysis of energy dispersive spectrometry (EDS) showed that the elements of Mg and Al distribute homogeneously in the Mg–Li–Al–Zn alloy, but the element Zn mainly locates at grain boundaries. The results of inductively coupled plasma analysis showed that the chemical compositions of Mg–Li–Al–Zn alloys are consistent with the phase structures of the XRD patterns, and that the lithium, aluminum, and zincum contents of Mg–Li–Al–Zn alloys depend on the concentrations of MgCl2, AlCl3 and ZnCl2.