A special mechanism of dislocation nucleation in deformed nanocrystalline metals and ceramics was described theoretically. The mechanism represented non-local homogeneous nucleation of a nanoscale loop of “non-crystallographic” partial dislocation whose Burgers vector magnitude continuously grew during the nucleation process. The dislocation loop nucleation was accompanied by nucleation and evolution of a generalized stacking fault bounded by the loop. It was shown that the special mechanism could effectively produce nanoscale loops of lattice dislocations in nanocrystalline metals (Al, Ni) and ceramics (3C–SiC) deformed at high mechanical stresses achieved in shock-wave and indentation load regimes.

Homogeneous Nucleation of Dislocation Loops in Nanocrystalline Metals and Ceramics. M.Y.Gutkin, I.A.Ovidko: Acta Materialia, 2008, 56[7], 1642-9