Enhanced formation of <100> and <111> interstitial loops by helium clustering in bcc iron

The nucleation and growth of helium (He) clusters in bcc iron (Fe) are simulated using molecular dynamics method. The self-interstitial atoms (SIAs) can be emitted from the He clusters, and the evolution of these SIAs depends on the spatial distribution of He clusters. A 1/2 < 111 > interstitial loop is presented from the emitted SIAs for the two He clusters separated far away from each other, but a < 100 > interstitial loop is formed at special conditions. A new mechanism for the formation and growth of a < 100 > interstitial loop in bcc Fe due to He clustering is proposed. (C) 2017 Elsevier B.V. All rights reserved.