A CALPHAD assessment of the Au-Cu system using the cluster variation method

A CALPHAD assessment of the Au-Cu system, based on using cluster expansion theory for the energy representation and tthe cluster variation method for the configuration entropy of the solid phase, has been carried out. This im proved modelling of the solid phases has been achieved within the Thermo-Ga le software package. An optimised thermodynamic description for the liquid and the disordered and ordered solid phases has been obtained. The assessme nt satisfactorily reproduces both the experimental phase diagram and the th ermodynamic properties for the liquid and solid phases, except for the enth alpy in the ordered state. A major challenge facing CALPHAD is to develop t echniques which will permit this kind of modelling to be used for multicomp onent systems.