Molecular dynamics simulation study of the effect of grain size on the deformation behavior of nanocrystalline body-centered cubic iron

A molecular dynamics simulation study has been carried out to clarify the effect of grain size on the deformation behavior of nanocrystalline body-centered cubic Fe. Average flow stresses were found to decrease with grain refinement below 14.7 nm, exhibiting a breakdown in the Hall-Petch relation. A change in the dominant deformation mechanism from dislocation glide to grain boundary sliding appeared to be the direct cause of the breakdown in the Hall-Petch relation observed in the present nanocrystalline pure Fe. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.