Thermodynamics of rare earth elements and uranium in gallium based quaternary metallic alloys

Thermodynamic properties of rare earth elements (Y, La, Nd) and uranium were experimentally determined in a number of quaternary alloys at 573–1073 K. Gallium based eutectic mixtures (Ga–Al, Ga–In and Ga–Zn) were chosen as the solvents. The systems studied were La–U–Ga–Al, La–U–Ga–In, La–U–Ga–Zn, La–Nd–Ga–In and La–Y–Ga–In. Activity of the metals in the alloys were determined employing the electromotive force measurements method with the electrolytes based on the ternary LiCl–KCl–CsCl eutectic containing chlorides of the elements studied. Solubility of uranium and lanthanum in La–U–Ga–In and La–U–Ga–Al alloys was determined from the chemical analysis of the saturated alloys, and activity coefficients were calculated from the difference of the temperature dependencies of activity and solubility. Composition of the intermetallic compounds formed in the alloys was assessed using X-ray diffraction analysis. The results obtained for the quaternary systems were compared with the corresponding ternary and binary systems.