Molecular dynamics methods were used to study the formation of vacancy clusters created by displacement cascades in α-Fe containing different concentrations of substitutional He atoms. Primary knock-on atom energies, Ep, from 0.5 to 20keV were considered at 100K, and the results were compared with those performed in pure α-Fe. There were distinct differences in the number and size of vacancy clusters within displacement cascades with and without substitutional He atoms. It was found that many large vacancy clusters could be formed within cascade cores in α-Fe with He atoms, in contrast to a few small vacancy clusters observed in pure α-Fe. The number and size of He/vacancy clusters generally increased with increasing He concentration and primary knock-on atom energy. One of the striking results was that the number of self-interstitial atoms and the size of interstitial clusters were much smaller than those in pure α-Fe.

Atomistic Simulation of Helium-Defect Interaction in Alpha-Iron. L.Yang, X.T.Zu, H.Y.Xiao, F.Gao, H.L.Heinisch, R.J.Kurtz, K.Z.Liu: Applied Physics Letters, 2006, 88[9], 091915 (3pp)