A study of the behavior of helium atoms at Ni grain boundaries

Using molecular dynamics simulations with an analytical embedded-atom method (MAEAM) model, the diffusion behavior of helium atoms at two Σ = 5 symmetric grain boundaries of Ni was investigated in the present paper. The simulations demonstrate that the interstitial helium atoms are stable at the grain boundaries. Helium atoms in Ni lattices could diffuse easily to the grain boundary and precipitate into a cluster, which confirmed the fact that helium atoms could nucleate and grow up into bubbles at the grain boundaries. The diffusion activation energy of interstitial helium atom at grain boundaries was also determined. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)