Atomistic modeling of the interaction between self-interstitial dislocation loops and He in bcc Fe

The effect of a helium atom on the migration of self-interstitial dislocation loops with a Burgers vector 1/2〈1 1 1〉 in bcc Fe has been investigated using molecular statics and molecular dynamics simulations. It is found that an interstitial He atom hinders the migration and coalescence behavior of dislocation loops by strongly binding to the loop on the edge sites. An unstable interstitial He atom on the loop plane easily moves to the stable edge sites by interstitial diffusion. A substitutional He atom does not significantly disturb the migration of dislocation loops, showing weak binding.