The constraints for the thermodynamic parameters of the type order–disorder transformation

A mathematical analysis of the constraints on the thermodynamic parameters of the compound energy formalism for an ( A , B ) m ( A , B ) n ↔ ( A , B ) m + n type order–disorder transformation is studied. Both the ordered phase and the disordered phase can be described using the two-sublattice model after the formula ( A y A ′ B y B ′ ) m ( A y a ″ B y B ″ ) n , with y i ′ = y i ″ ( i = A , B ) for the disordered phase and y i ′ ≠ y i ″ for the ordered phase. The constraints between the parameters for the ordered state were derived. The thermodynamic characteristics of the transformation are illustrated using a mathematical method and the validity of the model and the constraints is tested.