Irradiation Creep by Glide-Induced Transient Absorption

Abstract

Theoretical models for irradiation creep by climb-enabled glide of dislocations generally assume that steady-state profiles are maintained about a dislocation before, during and after the glide event. We show that, in fact, glide is too rapid to maintain steady profiles. The result is that there are significant transients in point defect flux to the dislocation associated with the termination of the glide event. Such transients propel dislocation climb excursions, which may lead to unpinning and to further glide resulting in irradiation creep. We term this new mechanism of irradiation creep glide-induced transient absorption. The solutions to the applicable time dependent diffusion equations are obtained. Calculations are carried out to identify the temperature ranges, materials, and irradiation parameter regimes where the mechanism is expected to be important. One consequence of the phenomenon is that it renders small dispersion hardening centers ineffective in restraining irradiation creep. 18 refs., 12 figs., 2 tabs.