It was noted that the effect of grain size on void swelling arose from the intrinsic properties of grain boundaries as neutral and unsaturable sinks for both vacancies and self-interstitial atoms. It had been demonstrated that grain-size dependent void swelling, measured under irradiation which produced only Frenkel pairs, could be satisfactorily explained in terms of standard rate theory and dislocation bias. On the other hand, experimental results had demonstrated that the effect of grain boundaries upon void swelling under cascade-damage conditions was markedly different and could not be explained in terms of standard rate theory. In order to understand the source of this difference, the effect of grain size upon void swelling under cascade-damage conditions was investigated - experimentally and theoretically - in pure Cu which was irradiated with fission neutrons at 623K, up to a dose of about 0.3dpa. The post-irradiation defect microstructure, including voids, was investigated by using transmission electron microscopy and positron annihilation spectroscopy. The evolution of void swelling was modelled within the framework of the production-bias model and standard rate theory. The grain-size dependent void swelling which was measured experimentally was in good accord with the theoretical results obtained by using the production bias model.

On Grain-Size Dependent Void Swelling in Pure Copper Irradiated with Fission Neutrons. B.N.Singh, M.Eldrup, S.J.Zinkle, S.I.Golubov: Philosophical Magazine A, 2002, 82[6], 1137-58