Deformation behavior and strengthening mechanism of Cu/Nb nanolayered composites: molecular dynamics simulation and experimental verification

Nanolayered composites exhibit outstanding mechanical properties due to unique continuous laminated structures and high-density interfaces inside the materials. However, the mechanical characteristics and underlying atomic-level deformation mechanisms of nanolayered composites are still unclear. Thus, the molecular dynamics (MD) simulations were employed to investigate the tensile deformation of non-equal layer thickness Cu/Nb nanolayered composites and emphasized the effects of individual layer thickness on mechanical properties and dislocations evolution behavior. The results revealed an important dependence on the individual layer thickness for the mechanical properties of nanolaminates. Atomic-scale microstructure analysis displayed that the Cu–Nb interfaces played a significant role in hindering dislocation propagation. As the layer thickness decreases, the number and density of dislocations significantly increase, and the average length decreases. Meanwhile, the interactions between dislocations and interfaces were significantly increased in the limited space in the inner layer leading to a significant increase in the hindering effect of dislocations. Therefore, it exhibited a significant strength enhancement for nanolayered composites as the thickness of individual layers decreased, which was highly consistent with the experimental results. This study provides valuable insights into the plastic deformation of nanolayered composites and gives theoretical guidance for the design of nanolayered composites.