It was recalled that the problem of void swelling was usually explained in terms of the production bias model. This took account of the intracascade clustering of vacancies and self-interstitial atoms, their thermal stability and the resulting asymmetry in the production of free and mobile vacancies and self-interstitial atoms. The model also considered the effect of the 1-dimensional diffusional transport of glissile clusters of self-interstitial atoms upon damage accumulation in the form of voids and defect clusters. An important prediction of the model was that, for a given irradiation temperature and damage rate, void swelling should depend very much upon the recoil energy, because the latter strongly affected the intracascade clustering of self-interstitial atoms and vacancies; especially at lower recoil energies. In order to test this prediction, pure and annealed Cu specimens were bombarded with 2.5MeV electrons, 3MeV protons or fission neutrons at about 520K. All 3 irradiation experiments were carried out using a similar damage rate (of the order of 10-8NRTdpa/s). The post-irradiation defect microstructures were investigated by using electrical resistometry, transmission electron microscopy and positron annihilation spectroscopy. The accumulation of defects in the form of planar clusters and voids was found to increase markedly with increasing recoil energy. This was in good agreement with the predictions of the production bias model.

On Recoil Energy Dependent Void Swelling in Pure Copper - I. Experimental Results. B.N.Singh, M.Eldrup, A.Horsewell, P.Ehrhart, F.Dworschak: Philosophical Magazine A, 2001, 80[11], 2629-2650