Solved and unsolved issues in the interpretation of SANS results obtained for neutron-irradiated Fe-Cr alloys

Full set of nuclear and magnetic SANS data for a number of four Cr levels, three dpa levels each, is presented. The results are given in terms of concentration, size and A-ratio as function of Cr and dpa. A consistent understanding is obtained for Fe12Cr in terms of alpha‘ phase formation. For Fe2.5Cr, Fe5Cr and Fe9Cr, the presence of a second kind of scatterers is indicated, to which impurity elements such as Ni, Si, and C must contribute. The nature of scatterers in Fe2.5Cr, Fe5Cr and Fe9Cr is among the unsolved issues. Candidates are Cr-C-enriched clusters and/or Cr-Si-P-Ni-enriched clusters detected by atom probe tomography. There is an inconsistency between composition reported for APT and composition assumed in the SANS analysis with respect to Cr/Fe-fraction.