Molecular dynamics simulations investigating the mechanical properties of nanocrystalline Al have revealed the importance of both dislocation nucleation at grain boundaries and subsequent propagation as possible rate-limiting microscopic plastic process. Here, an approach was presented for determining the athermal stress-strain behaviour of selected dislocations as they propagate within the nanocrystalline environment. In the first case study, the critical resolved shear stress to de-pin resulting into a planar propagation was found to be 735MPa. In a second case study, a pinned dislocation was found to cross-slip at a critical resolved shear stress of 372MPa to circumvent a near unfavoured grain boundary region.

Athermal Critical Stresses for Dislocation Propagation in Nanocrystalline Aluminium. C.Brandl, S.Tiwari, P.M.Derlet, H.Van Swygenhoven: Philosophical Magazine, 2010, 90[7-8], 977-89