The results of molecular dynamics simulations of the structure and deformation behavior of nanocrystalline materials (polycrystalline materials with a grain size of less than about 100nm) were reviewed. It was noted that such simulations had now become large and sophisticated enough to begin to cover the entire range of grain sizes over which the experimentally suggested transition from a dislocation-based deformation mechanism, to one which involved grain-boundary processes, took place. Their atomic-level resolution provided novel insights into the complicated interplay between the dislocation and grain-boundary processes that were responsible for the cross-over. The simulations also revealed how and why this cross-over in the dominant mechanism led to a transition in mechanical behavior. However, these simulations were inherently limited to the treatment of idealized model microstructures and of extremely high deformation rates.

Deformation of Nanocrystalline Materials by Molecular-Dynamics Simulation - Relationship to Experiments? D.Wolf, V.Yamakov, S.R.Phillpot, A.Mukherjee, H.Gleiter: Acta Materialia, 2005, 53[1], 1-40