Exact phenomenological theory for thermotransport in a solid binary alloy

In this paper, we study the theory of the diffusion behaviour of a binary alloy in a temperature gradient (thermotransport). Using the Onsager formalism of irreversible thermodynamics we develop exact relations for the heats of transport of each component in terms of various measurable diffusion quantities under steady state conditions and with the vacancies being at local equilibrium. Apparent inconsistencies with some earlier work are indicated. Further relations for heats of transport are then developed in terms of the random alloy model for the Darken and Manning approximations. Relations for the formal separation of the heats of transport are also developed.