Binding enthalpies of nitrogen-vacancy complexes in irradiated α-Fe

Dilute iron-nitrogen alloys have been irradiated at low temperatures with electrons or neutrons to varying doses. In the temperature range above Stage III (T≥200 K) a previously unknown family of small clusters composed of N interstitials and radiation-induced point defects, i.e. vacancies, could be resolved by means of a sensitive magnetic after-effect technique. Analysis of formation and dissociation kinetics of these clusters leads to nitrogen-vacancy binding energies between 0.08 and 0.5 eV, depending on cluster size. These relatively low values, together with further details of the precipitation kinetics, are shown to support the assumption of a two-interstitial recovery model. (author)