Partial and split dislocation configurations in nanocrystalline metals

A theoretical model is suggested that describes the generation of partial and split dislocations at grain boundaries in nanocrystalline metals. The ranges of parameters (such as grain size and level of external stress) are theoretically revealed at which the formation of partial dislocation semi-loops is energetically favorable. It is shown that anomalously wide stacking faults between partial dislocations-elements of split dislocations-are formed due to the effects of high stresses existing in nanocrystalline metals under mechanical load. The results of the suggested model account for experimental data on observation of partial and split dislocation configurations in nanocrystalline Al reported in the literature.