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

作者：Xiaoyu Sun, Vincent Taupin, C. Fressengeas, Patrick Cordier · 发表于：International Journal of Plasticity · 年份：2015 · DOI：10.1016/j.ijplas.2015.10.003 · 被引用次数：35 · 研究领域：Microstructure and mechanical properties、Metal and Thin Film Mechanics、Aluminum Alloys Composites Properties

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.