Dislocation emission by pores in nanocrystalline metals

A theoretical model is proposed to describe the emission of lattice and grain-boundary dislocations from pores in nanocrystalline metals during mechanical loading. In this model, dislocation emission occurs via an ideal nanoshear. A dislocation nucleates at a finite distance from a pore, and the modulus of its Burgers vector increases continuously from zero to the modulus of the Burgers vector of a lattice or grain-boundary dislocation. The applied stress and the critical pore-dislocation distance at which dislocation emission via an ideal nanoshear in nanocrystalline Ni, Al, and Cu becomes an energetically favorable and barrier-free process are determined.