The effect of He impurities on the properties and behavior of self-interstitial atom clusters in α-Fe was simulated by atomistic molecular dynamics and molecular statics simulation techniques using semi-empirical interatomic potentials and compared to ab initio electronic structure calculations. The molecular dynamics simulations revealed many interactions between He and self-interstitial atom clusters, including a spontaneous self-interstitial-atom/substitutional-He recombination and replacement mechanism that ejects He into interstitial positions and a strong interaction between He, in either interstitial or substitutional positions, with self-interstitial atom and self-interstitial atom clusters and also with other He atoms. The molecular statics calculations revealed relatively small interaction trapping radii of about 1nm between interstitial He and self-interstitial atom cluster complexes, but strong binding energies from 1.3 to 4.4eV; depending upon cluster size and interaction geometry. The comparisons between the ab initio and semi-empirical interactions were in generally good agreement and indicated that the He–point defect interactions in body-centered cubic Fe were well represented by considering the displacement (strain) field interactions amongst the defects.

Helium–Self-Interstitial Atom Interaction in α-Iron. L.Ventelon, B.Wirth, C.Domain: Journal of Nuclear Materials, 2006, 351[1-3], 119-32