Small-angle neutron scattering study of neutron irradiated Fe and Fe-Ni

Nickel plays a key role in the degradation mechanism of neutron-irradiated reactor pressure vessel steels. Binary Fe-Ni alloys are basic for understanding and modeling of the behaviour of more complex steels. The nature of irradiation-induced features in Fe-3wt%Ni was investigated by means of small-angle neutron scattering and Vickers hardness measurements and compared with results for commercially pure Fe. We have observed a vacancy-Ni ratio of 0.4 to 0.5 in the average scatterer. This finding is consistent with the hardness increase observed.