Molecular dynamics simulation of effects of interface imperfections and modulation periods on Cu/Ta multilayers

Molecular dynamics (MD) simulations were performed to study the effects of the interface imperfections and modulation periods (lambda) on deformation mechanisms of Cu/Ta nanoscale metallic multilayers (NMMs) under uniaxial tension. We found that the Cu(1 1 1)/Ta (1 1 0) interface can serves as the source for dislocation nucleation and the barrier impeding the motion of dislocations. The yield stress of Cu/Ta NMMs depends only on the material properties instead of the lambda. With the increase of lambda,more dislocations would store in the incoherent interface, resulting in larger local residual stress, and thus dislocations would be easier nucleate from the interface in Ta layer, so the maximum stress decreases with the increase of lambda. There is a critical lambda (about 11.18 nm), in which flow strength of the NMMs is maximized. In this stage, dislocations absorption in Ta layers and dislocations nucleation in Cu layers dominates the plastic deformation in the material, jointly. (C) 2017 Elsevier B.V. All rights reserved.