Thermodynamic evaluation of the ternary Ag–Au–Cu system—including a short range order description

The disordered and ordered phases of FCC-type in Ag–Au–Cu are described thermodynamically with a Gibbs energy expression for four sublattices. Using the compound energy formalism and nearest neighbour bond energies, it is possible to obtain a thermodynamic description that includes both short and long range order. The short-range order contribution to the Gibbs energy is connected to the bond energies through some reciprocal parameters, which allow mixing on two sublattices simultaneously. It is shown that the use of nearest neighbour bond energies in connection with the compound energy formalism will reduce the number of optimised parameters required and hence allow for better extrapolations.