The diffusion behaviors of helium atoms at two symmetrical grain boundaries (Σ5<001>{210} and Σ3<110>{112}) were investigated using molecular dynamics simulations through an analytical embedded-atom method model. The simulations demonstrated that the interstitial helium atoms were easily trapped at the grain boundaries and precipitated into clusters. Due to the closed-shell electronic configurations of both helium and palladium, Pd grain boundaries had a strong capability to retain helium atoms. By calculating the mean square displacements of an interstitial helium atom at the grain boundaries, the diffusion coefficients were determined, and the linear fits to Arrhenius relation. The diffusion activation energies of interstitial helium atom at these two Pd grain boundaries were also evaluated.

Diffusion Behaviors of Helium Atoms at Two Pd Grain Boundaries. Xia, J.X., Hu, W.Y., Yang, J.Y., Ao, B.Y.: Transactions of Nonferrous Metals Society of China, 2006, 16[2], s804-7