Dynamic Relaxation and New Periodic Symmetry Technique for Simulating Interactions Between Dislocations

Studies of the interaction between two edge dislocations have been carried out by coupled Dynamic Relaxation (DR) technique, the Embedded Atom method (EAM) potential function and a newly developed periodic symmetry method. The effects of boundary conditions and external tractions are examined for the case of edge dislocations with the same or opposite Burgers vectors gliding on physically the same planes, and for dislocations with opposite Burgers vectors gliding on parallel planes. The results show that as expected, edge dislocations dissociate into Shockley partials to minimize their energy. Depending upon the sign of the Burgers vector of component dislocations, various defect configurations are obtained after the relaxation. A more stable defect configuration replaces the well-known structure of the perfect dipole when the distance between the slip planes decreases. This leads to the formation of faulted dipoles in Z configuration. The relaxation results depend upon parameters such as dipole height, initial dipole configuration and also external tractions applied to the system. These parameters together with the atomistic mechanism of transformation of perfect dipole into the Z dipole are studied. The suitability of the technique for simulating complex defect structures in crystalline material is discussed.