Dislocation mechanism was still considered to be an effective way in plastic deformation of nanocrystalline materials. The possible nucleation of a screw dislocation from the triple junction was explored. The nucleation of a screw dislocation was found to be rather difficult from the triple junction with well-bonded grain boundaries due to the small singularity (0 to −1/3) introduced by the elasticity anisotropy. For the triple junction with a free sliding grain boundary, the stress singularity was higher than −0.5 and dislocations could be spontaneously nucleated for grain sizes less than 100 nm.

A Screw Dislocation Nucleated from a Triple Junction. H.Wang, W.Yang: International Journal of Plasticity, 2005, 21[11], 2053-70