Thermodynamic Investigation of Atomic Order in Molten K-Bi Alloys

Abstract

The assymmetry observed in the concentration dependence of the thermodynamic properties of K-Bi is investigated using an empirical model which assumes a process of heterocoordination. The model is further used to explain the concentration dependence of some thermodynamic properties viz.: free energy of mixing, heat of mixing and the excess entropy of mixing.

Our calculations in most cases yield qualitative agreement with experiment for all quantities investigated and are also used to supplement experimental data. We conclude by stating that the formation of the complex K₃ Bi is of a weak nature in the liquid phase. Compound formation persists at all concentrations but the K-rich end of the phase diagram is more ordered.

Key Words:

• Order parameter
• concentration fluctuation
• compound formation