Thermodynamics of mixtures and phase field theory

The phase ®eld model is considered as a special case of thermodynamics of a binary mixture. The customary jrcj2- term in the free energy is thus recognized as a term that represents the kinetic energy of the di€usive motion of the two phases. This interpretation deviates from the usual one by which the jrcj2-term represents a ``smeared-outʹʹ interfacial energy