The dynamic interaction between a coherent precipitate and an edge dislocation was analyzed by using a discrete atomistic method which was based upon classical statistical mechanics and linear elasticity. Precipitates which had a dilatational misfit strain, and elastic constants which were different to those of the matrix, were treated as anisotropic elastic systems under plane-strain conditions. It was noted that a coherent interface transformed into a semi-coherent one via the nucleation of dipolar dislocations at a stress concentration in a coherent precipitate. One of the dipolar dislocations then glided along the precipitate/matrix interface to become a misfit dislocation, while the other slipped into the matrix phase to become a lattice dislocation. In accordance with continuum elasticity theory, a coherent particle with a positive misfit strain migrated to the tensile side of an edge dislocation, whereas a particle with a negative misfit strain diffused to the compressed region. Morphological changes were caused by the dislocation, as the particle tried to optimise the dislocation stress field, and the particle shape depended upon its stiffness and elastic anisotropy. Under an applied shear, a hard coherent particle with a positive misfit strain was sheared along the shear direction, but a soft particle responded in the opposite direction. The elastic interaction between a coherent particle and an edge dislocation could be so strong that the particle-dislocation complex remained coupled even when a high shear strain was applied to the system. Some composite applied stresses could cause an edge dislocation to split into 2 partials. One of the partials (a glissile component) was found to be actively involved in the morphological evolution of a particle during diffusional relaxation.

Dynamic Interaction between a Coherent Precipitate and an Edge Dislocation J.K.Lee: Metallurgical and Materials Transactions A, 1998, 29[8], 2039-44