Diffusion of vacancies and interstitials to edge dislocations

Abstract

The steady-state diffusion of radiation-produced point defects in the stress field of an edge dislocation is solved by a perturbation method. The drift term entering the diffusion equation includes the size interaction and the inhomogeneity interaction as well as the effects of externally applied loads. By comparing the perturbation solution with the rigorous solution of Ham, we show that the perturbation solution is always adequate provided the drift term is proportional to the gradient of the interaction energy of the point defect with the dislocation. The steady-state distributions of vacancies and interstitials is such that voids or vacancy clusters preferentially grow on the compressive side of the edge dislocation. The external stresses give rise to an orientation-dependent bias of the edge dislocation which is shown to provide a possible mechanism for radiation-induced creep.

The Dislocation Bias

“…However, this solution applies only when the mobile defects is modeled as a center of dilatation. For more general interactions, Wolfer and Askin [22] developed a rigorous perturbation theory that includes also the interaction induced by externally applied stresses. The latter was shown to result in radiation-induced creep.…”

Irradiation Creep–Swelling Interaction in Modified 316 Stainless Steel up to 200 dpa

“…This swelling independent term has been well interpreted in terms of the stress-induced preferential absorption (SIPA) mechanism under active investigations for many years. The SIPA mechanism proposed by Heald and Speight 7) , Wolfer and Ashkin 8) , and Bullough and Willis 9) depends solely on differences in the climb rate of dislocations whose orientation relative to the applied stress influences their absorption of point defects. Dislocations with their Burgers vector parallel to the external stress direction can more easily absorb interstitial atoms and can take climb motion than those with their Burgers vector perpendicular to the external stress.…”

Radiation-induced stress relaxation in high temperature water of type 316L stainless steel evaluated by neutron diffraction

“…It is not clear why these A 3 coefficients vary among the materials. But considering the irradiation stress relaxation mechanism [15][16][17], it is likely that this difference is caused by a difference in dislocation mobility (kinetics, migration energy, interaction with point defects, etc.). In addition, difference of crystal system is also considered to be one of the reasons (austenitic stainless steel and nickel; f. c. c, Zircaloy-2; h. c. p).…”