Nanovoid growth in nanocrystalline metal by dislocation shear loop emission

Experimental evidence and molecular dynamics simulations of void growth indicate that dislocation shear loop emission is a viable mechanism of void growth. Based on this mechanism, a theoretical model to describe the growth of nanovoid at triple junction of nanocrystalline metal under equal biaxial remote stress is suggested. In this model, it is proposed that emission of dislocation is caused by the interaction between applied stress and image stress introduced by existing nanovoids. The critical stress is derived for emission of dislocation by considering the effects of surface stress. Within our description, dislocations emitted from surface of nanovoid are stopped at grain boundaries and the stress field generated by arrested dislocations can prevent further dislocation emission. The maximum number of dislocations emitted from surface of nanovoid, as a representation of the nanovoid growth, is analyzed as a function of grain size.