Electrochemical preparation of ternary Mg–Li–La alloys from LiCl–KCl–MgCl2–LaCl3 melts

Abstract

Direct electrodeposition of ternary Mg–Li–La alloys on a molybdenum electrode from LiCl–KCl–MgCl2–LaCl3 melts at 943 K was investigated. Cyclic voltammograms showed that the underpotential deposition of lithium on predeposited Mg–La alloy leads to the formation of Mg–Li–La alloy. Chronopotentiometric measurements indicated that the codepositon of Mg, Li and La occurs at current densities more negative than −0·62 A cm−2. The microstructure of Mg–Li–La alloys was analysed by X-ray diffraction, optical micrograph and SEM. The X-ray diffraction analysis indicated that α+Mg17La2, α+β+Mg17La2 and β+LaMg3 Mg–Li–La alloys with different lithium and lanthanum contents were obtained via galvanostatic electrolysis with different concentrations of MgCl2. The results of SEM suggested that element La exists at grain boundaries to restrain the grain growth rate.