| A theoretical model is suggested which describes the role of nanoscale voids (nanovoids) as sources of dislocations in single-phase and composite nanocrystalline materials during plastic deformation. In the framework of the model, lattice and grain boundary (GB) dislocations are emitted from nanovoids under the shear stress action. The characteristic values of the flow stress needed to initiate dislocation emission from nanovoids are estimated and shown to be close to those that characterize plastic flow in nanocrystalline materials. With the results of the suggested theoretical model, the effects of nanovoids on deformation and fracture processes in single-phase and composite nanocrystalline materials are discussed. |
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