Layer size effect on the shock compression behavior of fcc-bcc nanolaminates

Using large-scale nonequilibrium molecular dynamics simulations, we study the roles of interfaces and layer thickness in the response of experimentally observed Cu/Nb nanolayered composites to shock compression. We observe a critical layer thickness (<20 nm) below which lattice dislocations nucleate preferentially from the Cu/Nb interfaces. Within this regime of interface dominance, samples with a layer thickness of 5 nm have the largest Hugoniot elastic limit (the critical shock pressure required for dislocation production), which then decreases for finer layer thicknesses, where dislocation transmission across the interfaces becomes more frequent. The dislocation slip systems emitted and transmitted across the interfaces are strongly linked to the interface structure and crystallography. The strong layer thickness and interface structure effects found here can provide insight for the design of shock-resistant nanolayered composites.