Enhanced co-deformation of a heterogeneous nanolayered Cu/Ni composite

Abstract

Nanolayered metallic composites have attracted intensive scientific interests due to their ultrahigh strength. However, the deformation incompatibility among the component layers with high mechanical contrast leads to extremely low tensile ductility in the nanolayered composites, which is a great setback for their engineering applications. Here, by molecular dynamics simulations, we show that a heterogeneous nanolayered design by combining 2.5 nm and 24 nm Cu/Ni bilayers in a composite in an appropriate way can promote the dislocation activity of the hard phase, i.e., the Ni layers. In the new heterogeneous structure, each 24 nm Cu or Ni layer is coated on both surfaces by one 2.5 nm Cu/Ni bilayer. The simulations show that the dislocations in the 24 nm Ni layers can nucleate and glide almost synchronously with those in the 24 nm Cu layers. The enhanced dislocation activities are attributed to the presence of the 2.5 nm Cu layer that can promote the dislocation nucleation and motion in the 24 nm Ni layer by forming more nodes in the dislocation network of the interface.