The migration of helium on different <110> high angle tilt grain boundaries with misorientation angles from 26° to 140° in α-Fe was studied using atomistic simulations with Fe-He potentials. Systematic molecular static and molecular dynamics simulations were performed in order to calculate the binding energy between He and grain boundaries, to estimate the diffusion coefficient and characterize migration mechanisms. The thermal stability of grain boundaries was studied as well. The simulations were performed at 300 to 1200K. The results showed that all the grain boundaries studied were stable up to 1200K; both interstitial and substitutional helium were strongly bound to tilt grain boundaries and the particular binding energy strongly correlated with the excess volume. The obtained results demonstrated that the migration mechanism and diffusivity of interstitial He were extremely sensitive to variations in atomic structure of the grain boundaries.

Molecular Dynamics Simulation of Interstitial He Diffusion on <110> Tilt Grain Boundaries in α-Iron. He, X.F., Terentyev, D., Yang, W.: Atomic Energy Science and Technology, 2012, 46[5], 513-9