Experimental thermodynamic investigation of the liquid Cu-Li-Sn system by Knudsen Effusion Mass Spectrometry

Abstract

The thermodynamic activity of lithium was measured by Knudsen Effusion Mass Spectrometry (KEMS) within the Cu-Li-Sn system in the liquid region. For this purpose, eleven samples were studied between 773 and 1078 K in the Sn-rich part of the Cu-Li-Sn phase diagram. Mixing enthalpies, entropies and Gibbs energies were derived directly from the measured thermodynamic activity. The measured thermodynamic activities of Li were fitted to the Redlich-Kister-Muggianu (RKM) sub-regular solution model, by taking ternary interactions into account, using a mathematical regression procedure. Thereby, the partial and integral excess thermodynamic properties, the activities of Li, Cu and Sn and the ternary interaction L-parameters, as a function of temperature, were obtained.