EQUIVALENCE OF THE GENERALIZED BOND-ENERGY MODEL, THE WAGNER-SCHOTTKY-TYPE MODEL AND THE COMPOUND-ENERGY MODEL FOR ORDERED PHASES

The equivalence of three thermodynamic models used in the literature t o describe the compositional and temperature dependencies of the therm odynamic properties of ordered intermetallic phases is presented. The three models are the generalized bond-energy model, the Wagner-Schottk y-type model and the compound-energy model. Equations to convert the m odel parameters of the generalized bond-energy model to those of the o ther two models are derived. The validity of these equations is demons trated by showing the successful conversion of the model parameters fo r the ordered phases in the To-Al system from the generalized bond-ene rgy model to those of the Wagner-Schottky-type model and the compound- energy model. However, conversion of the model parameters from these t wo models to the generalized bond energy model is generally not possib le due to additional constraints imposed in developing the later model .