期刊
ACTA MATERIALIA
卷 55, 期 1, 页码 261-271出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2006.07.023
关键词
nanocrystalline materials; micromechanical modelling; grain boundary; plastic deformation
In this paper we present a micromechanical approach based on fast Fourier transforms to study the role played by dislocation glide and grain boundary (GB) accommodation in the determination of the plastic behavior of nanostructured materials. For this, we construct unit cells representing self-similar polycrystals with different grain sizes in the nanometer range and use local constitutive equations for slip and GB accommodation. We study the effect of grain size, strain rate and pressure on the local and effective behavior of nanostructured Ice materials with parameters obtained from experiments and atomistic simulations. Predictions of a previous qualitative pressure-sensitive model for the effective yield strength behind a shock front are substantially improved by considering strain partition between slip and GB activity. Under quasiestatic conditions, assuming diffusion-controlled mechanisms at GB, the model predicts a strain-rate sensitivity increase in nanocrystalline samples with respect to the coarse-grained material of the same order as in recently published experiments. Published by Elsevier Ltd on behalf of Acta Materialia Inc.
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