Nanotwins induced by grain boundary deformation processes in nanomaterials

A special physical mechanism for the formation of nanoscale deformation twins in nanocrystalline and ultrafine-grained materials is suggested and theoretically described. The mechanism represents the cooperative emission of partial dislocations from grain boundaries (GBs) which is preceded and induced by both GB sliding and stress-driven climb of GB dislocations. The energy and stress characteristics of the nanotwin formation through cooperative emission of dislocations from GBs in nanocrystalline nickel and silicon carbide are calculated and discussed.