The thermodynamic modelling of carbide, nitride and carbo-nitride phases ha
s been reviewed and recommendations made. A comprehensive list of assessed
phases has been made with a bibliography. Recommended, estimated values for
metastable phases have been tabulated. A new method of predicting phase st
ability of ordered phases has been outlined. This involves the coupling of
CVM (cluster variation method) and mean field approximation calculations. A
pplication to the Nb-C system is discussed.