Prediction of Solid + Liquid Equilibrium Diagrams for Binary Mixtures Forming Solid Solutions with an Extremum

Abstract

ABSTRACTConvenient methods of correlation and prediction of S+L diagrams exist only for systems forming eutectics. To deal with solid solutions, we have adopted the model of strictly regular solutions of Guggenheim [3–5]. Our key assumption is that values of the Gibbs function of interchange w are different in the two coexisting phases: wS and wL. The assumption is based on the fact that the average interatomic distances R are also different, and this affects the averages of the interatomic (or intermolecular) potentials. The input parameters are enthalpies and temperatures of melting of pure components and any pair of experimental points on the diagram. For a number of binary alloy systems the agreement with the experiment is good. Since we believe in the basic unity of materials (see Chap. 1 in [7]), calcuations have also been made for organic mixtures, again with good results.