Analysis of diffusion in metals based on non-equilibrium thermodynamics

Abstract

A general form of the first Fick law for diffusion in single-phase metallic alloys is obtained by the methods of non-equilibrium thermodynamics. Because the vacancies are treated as an independent component, the reactions for the creation of vacancies are considered. The electrons are also treated as a component, and therefore an internally generated electric field appears in the generalized equation, in addition to the usual externally applied electric field. Similarly, two types of temperature gradient are considered; consequently, even in nominally “isothermal” diffusion a gradient in temperature may exist. The power of an analysis based on non-equilibrium thermodynamics is shown by the fact that the resulting equations have produced solutions to three previously unresolved problems.