Preparing different phases of Mg-Li-Sm alloys by molten salt electrolysis in LiCl-KCl-MgCl2-SmCl3 melts

Different phases of Mg-Li-Sm alloys were prepared by galvanostatic electrolysis in LiCl-KCl-MgCl2-SmCl3 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 SmCl3. 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.%.