Molecular dynamics simulations were reported which investigated the effect of 2 parallel free surfaces on the deformation mechanisms of model nanocrystalline face-centered cubic materials. The purpose of the simulation was to determine which phenomena, observed in in situ tensile experiments performed in an electron microscope, could be expected to be intrinsic properties of the deformation process and which phenomena resulted from the thin-film geometry required to obtain high-resolution transmission electron microscopic contrast and resolution. It was found that, in nanocrystalline samples

with thin-film thicknesses that were comparable to those used in experiments, the extent of influence of the surface was of the order of the grain size. For a sample with a mean grain size of 5nm, this was reflected by an increase in intergranular deformation (sliding) at the surface. For a sample with a mean grain size of 12nm, in addition to increased sliding at the surface, there was a significant increase in dislocation activity that extended throughout the sample.

The Role Played by Two Parallel Free Surfaces in the Deformation Mechanism of Nanocrystalline Metals - a Molecular Dynamics Simulation. P.M.Derlet, H.Van Swygenhoven: Philosophical Magazine A, 2002, 82[1], 1-15