PNNL

Abstract

Extended abstract based on a manuscript submitted to Philosophical Magazine & Philosophical Magazine Letters for publication [1]. The preferential attraction to sinks of self-interstitial atoms (SIAs) over that of vacancies is the fundamental cause of the void swelling, and ultimately the evolution of microstructure in irradiated material. This preferential attraction is described mathematically in terms of bias factors that can be evaluated by solving diffusion equations for point defects (PDs) with drift terms included. The dislocation bias deduced from theory can be on the order of 0.5-1 (increasing with increasing sink strength) in a marked contrast with phenomenological values of 0.01-0.005 assumed in the early rate theory models in attempt to explain experimentally observed swelling rates [2]. Later this became one of the reasons that prompted the development of models based on production bias (PBM) as the main driver for swelling, which assumed that the dislocation bias was much lower than that predicted by theory. However, the PBM in its present form fails to account for important and common observations: the indefinite void growth often observed under cascade irradiation and the swelling saturation observed under high dose irradiation and in void lattices.