Atomistic calculations were used to model the nucleation of partial dislocations, during tensile deformation, from bicrystal interfaces with a dissociated structure. Interfaces with this type of structure occurred mainly in materials with a low intrinsic stacking-fault energy. The initial structure of each bicrystal interface was refined here by using energy minimization techniques. Molecular dynamics simulations were then used to study the constant strain-rate deformation of each interface under uniaxial tension perpendicular to the boundary plane. The analysis focused on the evolution of the dissociated interface structure before dislocation nucleation, and the resultant structure of the boundary following the emission of partial dislocations from the interface. Dislocation nucleation occurred mainly at the dissociated-interface structural unit, while the spacing between interface features was identified as an important length scale that affected the failure mode. The evolution of the dissociated interface structure and the nucleation of partial dislocations were found to be similar to results obtained in a previous atomistic study of the stress dependence of a lock formation containing a stair-rod dislocation.

Dislocation Nucleation from Bicrystal Interfaces with Dissociated Structure. D.E.Spearot, K.I.Jacob, D.L.McDowell: International Journal of Plasticity, 2007, 23[1], 143-60