Vacancy and substitutional solute distribution around an edge dislocation in equilibrium and in steady-state glide motion

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Abstract
The equilibrium vacancy and solute distribution around an edge dislocation in a non-ideal, substitutional, multicomponent solid solution of arbitrary composition is determined. The equilibrium condition that the free energy of the system should remain unchanged when an atom of any component located inside the elastic field of the dislocation exchanges positions with a vacancy located far from the dislocation is used. A set of equilibrium conditions whose simultaneous solution gives the equilibrium vacancy and solute distribution is found. The well-known formulae for ideal and dilute binary solutions are recovered as special cases of the general formulation. The equations governing the steady-state vacancy and solute distribution around a gliding edge dislocation are found for a non-ideal, non-dilute substitutional binary solid solution. By considering the fact that no sources or sinks for vacancies are present in the field of a gliding edge dislocation, the equation governing the flux of solute atoms in the frame of reference of the moving dislocation is found. The relevant diffusion coefficient for solute-drag-controlled creep is obtained and the boundary value problem to be solved to find the steady-state solute distribution around the dislocation is stated. The solute drag force on the gliding dislocation is obtained from the power dissipated by the diffusional process.

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