The effects of grain boundary structure on binding of He in Fe

Computer simulations were performed to explore the effect of grain boundary (GB) structure and properties on the binding of He to boundaries in Fe. Symmetrical tilt GBs spanning a range of GB energies and excess volumes were examined. Molecular statics was used to map the He trapping efficiency at numerous substitutional and interstitial sites in and near each GB. The results showed that both substitutional and interstitial He atoms were trapped at GBs. Interstitial He was more strongly bound ({approx}0.5 to 2.7 eV) to the GB core than substitutional He ({approx}0.2 to 0.8 eV). The He binding energy was found to increase linearly with GB excess volume. The He capture radius varied from {approx}0.3 to 0.7 nm and also depended on GB properties. Finally, the He binding energy varied significantly within the GB core and approximately corresponded to the variation in atomic excess volume normal to the GB plane.