In situ TEM observations of room temperature dislocation climb at interfaces in nanolayered Al/Nb composites

Using in situ nanoindentation, we investigated dislocation-interface interactions in Al/Nb multilayers. Preferential storage of dislocations at interfaces, as opposed to within layers, was observed. Recovery of dislocations was observed to occur through climb in the interfaces. The rapid climb of dislocations is ascribed to high vacancy diffusivity and vacancy concentration in the interfaces. The vacancy formation energy at interfaces, 0.12 eV, as estimated from the experimentally measured climb rates, was found to be significantly lower than in the bulk.