Strain gradient crystal plasticity: size-dependentdeformation of bicrystals

Abstract The role of the grain boundary in influencing the deformation of a bicrystal isexplored using a rate-dependent crystal formulation of the Fleck–Hutchinson strain gradientplasticity theory. The physical basis of the theory is the elevated strengthening of a slip systemdue to geometrically necessary dislocations, associated with spatial gradients of slip. The theoryis implemented within the finite element framework and is used to study the deformation of abicrystal under in-plane shear loading. Contrary to classical scale-independent crystal plasticitytheories, the strain gradient theory predicts that the deformation state depends strongly upongrain size. Strain gradient effects are pronounced within a narrow layer at the grain boundary of abicrystal, and a significant grain-size dependence of the yield strength is predicted.

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