Electrical resistivity increase rates in Fe-C and Fe-N solid solutions during neutron irradiation at 4.5 K

A series of α-iron specimens containing carbon and nitrogen in interstitial solid solution were irradiated simultaneously at 4.5 K with fast neutrons to a fluence of 4.7 × 1017 n/cm2 with E > 0.1 MeV. In situ electrical resistivity measurements during irradiation showed that the apparent damage rates were dependent on the C or N concentration. In particular, the value of the initial resistivity increment per unit flux (S), passed through a minimum value at 0.1 at. per cent N and became larger than the value for pure iron above 0.14 at. per cent N. The results can be explained qualitatively as interstitial impurity-induced differences in production rates and dispersion of defects or semi-quantitatively as defect-induced deviations from Matthiessen's rule.