Comparative small-angle neutron scattering study of neutron-irradiated Fe, Fe-based alloys and a pressure vessel steel

Irradiation-induced damage in reactor pressure vessel steels covers a multitude of different features at the nanometer size scale. The nature, formation kinetics and relative importance of these features are not yet well understood in detail. It also turned out that there is no single experimental technique capable of closing all the remaining gaps. The present approach is based on the idea that significant progress can be achieved by investigating the same set of neutron-irradiated model alloys of increasing complexity with several experimental techniques including transmission electron microscopy (TEM), atom probe tomography (APT), positron annihilation spectroscopy (PAS) and small-angle neutron scattering (SANS). The aim of the effort is to explore both complementarity and overlaps of the information gained from individual techniques and to close gaps by introducing proper models. In the present paper the results obtained by means of SANS are reported, self-consistent interpretation is given and the results are qualified for the discussion in combination with the other experimental techniques to be given in separate papers.