Stochastic effects on dislocation structure development under cascade-damage irradiation

Dislocation climb, loop growth, and void swelling in the presence of the continuous generation of intracascade primary clusters are considered in this paper. Due to the random nature of cascade initiation, annihilation of point defects at sinks undergoes continuous random fluctuations that often have sizes comparable to the sizes of the primary clusters. This makes them particularly important to the evolution of small defect clusters. In this paper, a reaction kinetics approach is generalized to include the effects of stochastic fluctuations of point-defect fluxes introduced by the random point-defect production in discrete packages during cascade irradiation. The reaction constant consistent with this approach is derived for the annihilation of immobile clusters by the climbing dislocations. Taking the immobile primary interstitial clusters (PICs) as the interstitial loop nuclei, the evolution of loops and network dislocations, and the resulting void swelling are calculated as a function of dose. Using parameters appropriate to stainless steel, the loop number density, loop size distribution, network line density, and corresponding swelling are calculated and compared with experimental observations. It is found that this calculation explains the observations very well. © Springer-Verlag 1998.