Electrochemical formation of Sc-Al intermetallic compounds in the eutectic LiCl-KCl. Determination of thermodynamic properties

•The formation mechanism of AlxScy intermetallic compounds was studied in the eutectic LiCl-KCl•The formation energy, global and consecutive formation constants of AlxScy were estimated from OCP.•XRD after potentiostatic electrolysis, allowed the identification of Al3Sc and Al2Sc•XRD after intermittent galvanostatic electrolysis allowed the identification of Al3Sc, Al2Sc and AlSc2•SEM with EDX, allowed the identification of Al3Sc, Al2Sc, AlSc and AlSc2. The electrochemical formation of Sc-Al alloys was investigated in the eutectic LiCl-KCl by cyclic voltammetry and open circuit chronopotentiometry. On reactive Al electrode the electrochemical reduction of Sc(III) was observed at less cathodic potential values than at the surface of an inert W electrode, the potential shift is caused by the decrease of Sc activity in the metal phase due to the formation of Sc-Al intermetallic compounds at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sc(III) and Al(III) ions, using a W electrode, and ii) Sc(III) ions using an Al electrode. Analysis of the samples after electrolysis runs by X-ray diffraction allowed the identification of Al3Sc and Al2Sc, whereas analysis by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al3Sc, Al2Sc, AlSc and AlSc2. The formation energy of each AlxScy intermetallic compound, and the global and stepwise formation constant were estimated from open circuit chronopotentiometry measurements in the eutectic LiCl-KCl at 723 and 773K using Al as working electrode.