Nanocrack generation at dislocation-disclination configurations in nanocrystalline metals and ceramics

A theoretical model is suggested which describes the generation of nanoscale cracks in deformed nanocrystalline metals and ceramics. In the framework of the model, cracks are generated in the superposition of the stress fields of interfacial edge dislocations and disclination dipoles formed at interfaces (grain and interphase boundaries) during plastic deformation of nanocrystalline metals and ceramics. It is theoretically shown that the generation of cracks at such dislocation-disclination configurations is energetically favorable in nanocrystalline Ni and nanoceramics, 3C-SiC and alpha-Al2O3, in wide ranges of their structural parameters.