Effect of dislocation source length on yield strength of nanostructured metallic multilayer thin films

There is great interest in metallic multilayer thin films with the layer thickness on the order of nanometers due to their high hardness and strength. The yield strength deviates from Hall–Petch and Orowan predictions with layer thickness as the controlling factor, and other factors are in need to explain this phenomenon. In this work, the effect of dislocation source length on yield strength of multilayer system in the nanoscale regime is investigated using a three dimensional cellular automaton dislocation model. Different initial dislocation source lengths are assumed in the model for the metallic multilayer thin films with different layer thicknesses. The multilayer system studied here is composed of alternating A and B components with FCC structure, cube-on-cube orientation relationship, and the same layer thickness. The results show that the initial dislocation source length can provide an explanation for the above deviations.