| A theoretical model is suggested which describes the generation of nanocracks at grain boundaries and their convergence into a catastrophic macrocrack in nanocrystalline materials deformed by grain boundary sliding. The criterion for the convergence is revealed, and the fracture strength of a nanocrystalline material is calculated which characterizes the formation of a catastrophic macrocrack due to the convergence. Also, we estimated strain-to-failure controlled by grain boundary sliding, generation of nanocracks and their convergence. It is shown that both the fracture strength and strain-to-failure of a nanocrystalline material deformed through grain boundary sliding are highly sensitive to the misorientation angles of grain boundaries that dominate in the material. |
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