Influence of nanoscale amorphization on emission of dislocations from a finite length crack tip in nanocrystalline materials

The interaction between nanoscale amorphization and crack in deformed nanocrystalline materials is investigated. Effects of nanoscale amorphization characterized by three disclination dipoles on the emission of lattice dislocations from the crack tip are theoretically investigated. The critical stress intensity factors (SIFs) for dislocation emission from the crack tip are calculated. The influences of nanoscale amorphization as well as crack length on the critical SIFs are discussed in detail. The results show that nanoscale amorphization can suppress lattice dislocation emission. The most probable angle of dislocation emission decreases with increment of disclination strength and the shorter length crack drivers easier the dislocation emission from the crack tip.