The effect of interfaces on the mechanical behaviour of multilayered metallic laminates

The mechanical response of multilayered metallic laminates is dominated by size effects through the confinement of dislocation motion within the layers. We deconvolute the contributions to the plastic behaviour resulting from dislocation–dislocation interactions and dislocation–interface interactions, using discrete dislocation dynamics and atomistic simulations. Upper and lower bounds for the material strength are found by considering two limiting cases for the influence of the interfaces: hard and shearable. Hard interfaces, preserving interfacial dislocations, are shown to significantly increase the strength of the multilayered metallic laminates, whereas a deformable interface results in lesser hardening. Molecular dynamics simulations show that the {1 1 1}_Cu ∥ {1 1 0}_Nb Cu/Nb interface response lies between these two cases. Additionally, the plastic response of Cu/Nb multilayered metallic laminates is studied and shown to be isotropic due to an effect of averaging among layers, despite the plastic anisotropy of the respective layer materials. (paper)