Emission of partial dislocations from amorphous intergranular boundaries in deformed nanocrystalline ceramics

A theoretical model is suggested that describes emission of partial lattice dislocations from amorphous intergranular boundaries into crystalline grains in deformed nanocrystalline ceramics. Within the model, a dipole of immobile lattice dislocations is generated at an amorphous intergranular boundary through local shear events in this boundary. One of the dislocations then undergoes transformation, resulting in emission of a partial dislocation into a grain. It is shown that the emission process is energetically favorable in nanoceramic SiC deformed at high stresses.