Formation process of dislocation loops in iron under irradiations with low-energy helium, hydrogen ions or high-energy electrons

Formation processes of interstitial-type dislocation loops (I loops) in high-purity Fe under irradiations with 5 keV H+ ions or 1000 keV electrons are examined by in situ transmission electron microscopy at temperatures below room temperature, and the results are compared with that obtained under He+ ion irradiation. For the electron irradiation, conventional model of I-loop nucleation based on the assumption that di-interstitial atoms are stable nuclei of I loops is questioned. The volume density of I loops by H+ ion irradiation is one-order of magnitude higher than that by electron irradiation, and several times lower than that by He+ ion irradiation. The temperature dependence of the volume density of I loops by H+ ion irradiation supports the idea that such enhancement of I-loop formation is due to trapping of self-interstitial atoms by gas atom-vacancy complexes.