Effect of Interface Orientation and Loading Direction on the Mechanical Response of Cu-Nb Multilayered Nanocomposites

This work elucidates the effect of interface orientation, loading mode, and crystallography on the deformation mechanisms of Cu-Nb multilayered nanocomposites with interface structures from physical vapor deposition (PVD). Uniaxial tension and compression tests were performed using molecular dynamics simulations at room temperature. The simulations were utilized to understand the atomic-scale deformation mechanisms of tension and compression during iso-stress and iso-strain loading conditions. The Cu-Nb nanocomposites exhibit a typical tension–compression asymmetry with higher maximum compressive stress than the maximum tensile stress. In addition, the interface was shown to act as a dislocation nucleation source during iso-strain tension, and the pre-existing stacking faults were emitted during iso-strain compression, indicating different deformation mechanisms during tension and compression. Under compression normal to the interface and tension normal to the interface, unusual dislocation and twin interaction were observed, where slip transmission occurs from {111} slip planes to the unusual {100} slip-plane inside the 4-layer twin lamella. Furthermore, it was shown that the interface structures from PVD exhibit high stability against the deformation where failure was observed inside the Cu layer of the bi-metal composite.