Concentration Fluctuations in Liquid Alloys of Alkali Metals from Semiempirical Theories of Mixtures

The semiempirical theories of mixtures developed by van Laar, Margules, Scatchard-Hamer, Wilson and Renon and Prausnitz are used to study the concentration fluctuations of binary liquid alloys formed among the alkali metals. Examination of the fitting capabilities of these theories leads to the conclusion that those of van Laar, Scatchard-Hamer and Renon and Prausnitz are appropriate both when the atomic sizes of the component metals are similar and when there is considerable atomic size mismatch. The Margules and Wilson theories, on the contrary, appear to be restricted only to cases in which the size difference between the two types of atoms is small.