Formation of stable sessile interstitial complexes in reactions between glissile dislocation loops in bcc Fe

Clusters of self-interstitial atoms can be formed directly in high-energy displacement cascades or by growth. The majority are glissile dislocation loops and migrate by fast one-dimensional glide. We present results of a molecular dynamics (MD) study of reactions involving glissile interstitial loops in bcc-iron. We demonstrate that the reactions can produce a number of specific, stable microstructural features. Reactions between the most common glissile clusters of crowdions result in coarsening or formation of immobile interstitial complexes. Coarsening leads to a decrease of the total dislocation-line length and therefore is favourable. The structure and stability of the formed junction has been studied. No evidence of the formation of a loop from two glissile clusters was found. The formed immobile interstitial complexes have, however, high binding-energies (tens of eV), implying a relatively long lifetime. So, such objects are expected to contribute to the microstructure evolution under irradiation.