Diffusion of Lattice Defects in a Stress Field

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Abstract
The diffusion of lattice defects in a stress field produced by other defects such as dislocations, precipitates, or other point defects is considered. It is shown by calculation that in addition to the Einstein term which results from the force on the defect there is another term resulting from the influence of strain on the saddle-point configuration. This alters the migration energy. Detailed calculations for vacancy migration show that vacancy migration energies may be altered by 10%. The additional terms which should appear in the expression for the diffusion current are obtained. The diffusion equation is also modified by the appearance of additional terms, which are calculated. Finally, experimental evidence for changes in the migration energies of lattice vacancies, of divacancies, and of interstitials is described.