Continuous description of the atomic structure of grain boundaries using dislocation and generalized-disclination density fields

XY Sun and V Taupin and C Fressengeas and P Cordier, INTERNATIONAL JOURNAL OF PLASTICITY, 77, 75-89 (2016).

DOI: 10.1016/j.ijplas.2015.10.003

An atomistic-to-continuum method is developed to derive dislocation, generalized-disclination density fields and the associated elastic strain, rotation, curvature and second-distortion fields from the atomic structure of grain boundaries. From the relaxed and un-relaxed atomic positions, calculation of the transformation gradient feeds a mechanical framework, where discontinuities of the lattice elastic displacement and distortion (rotation and strain) are captured by smooth incompatible strain and second distortion fields associated with the dislocation and generalized-disclination density fields, respectively. The method is applied to a copper symmetrical tilt boundary as obtained from molecular dynamics simulations. The core structure of the boundary is found to contain edge dislocations and dipoles of generalized-disclinations, including standard wedge-disclination dipoles. The latter reflect in particular localized shear and stretch discontinuities across the interface, in addition to the overall rotation discontinuity. (C) 2015 The Authors. Published by Elsevier Ltd.

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