Elastic fields of a core-spreading dislocation in anisotropic bimaterials

Abstract

A dislocation at an interface especially at a weak shear interface spreads its core associated with shearing the interface. Such core-spreading significantly reduces stress/strain concentration of the dislocation at the interface and thus traps the dislocation in the interface, correspondingly strengthening materials. Employing the Green's function for a single dislocation, we derived analytical expressions for the elastic fields associated with a core-spreading dislocation in anisotropic bimaterials. We proposed three fractional dislocation models to mimic the spreading core of a dislocation at an interface, i.e. uniform distribution (UD), linear distribution (LD) and cosine distribution (CD). The accuracy and efficiency of the three fractional models are validated by the continuity of both traction and displacement across the interface. Numerical results of the stress and displacement fields of the dislocation in the Cu/Nb bimaterial show that: (1) such core-spreading greatly reduces the stress intensity near the dislocation compared with the dislocation with a condensed core; (2) the distribution of the Burgers vector associated with the core spreading determines the magnitude and patterns of the elastic fields; (3) The influence of the core-spreading on the elastic fields can be negligible when the distance of a field point from the center of the dislocation core is greater than 2.17 times the width of the spreading core; (4) The LD model is simple while it is able to capture the interaction force acting on an incoming dislocation. The findings offer insights into understanding interface roles in strengthening materials and designing interfaces-dominated composites.