Fracture mechanisms of symmetrical tilt grain boundaries

The mechanisms of failure of symmetrical tilt boundaries have been investig ated using an atomistic technique. The fracture process advances in steps t hat are related to the structural unit of the symmetrical tilt grain bounda ry. These boundaries are shown to fail through a combined mechanism involvi ng dislocation emission in certain regions of the structural unit, followed by microcleavage, and again dislocation emission. The overall toughness of the boundaries is given by the combination of the toughness of these two p rocesses.