Lattice dislocation induced misfit dislocation evolution in semi-coherent {111} bimetal interfaces

Abstract

The study of dislocation plasticity mediated by semi-coherent interfaces can aid in the design of certain heterostructured materials, such as nanolaminates. The evolution of interface misfit patterns under complex stress fields arising from dislocation pileups can influence local dislocation/interface interactions, including effects of multiple incoming dislocations. This work utilizes the Concurrent Atomistic-Continuum modeling framework to probe the evolution of misfit structures at semi-coherent Ni/Cu and Cu/Ag interfaces impinged by dislocation pileups generated via nanoindentation. A continuum microrotation metric is computed at various stages of the indentation process and used to visualize the evolution of the interface misfit dislocation pattern. The stress state from approaching dislocations induces mixed contraction and expansion of misfit dislocation structures at the interface. A lower number of misfit nodes per unit interface area coincides with greater localized deformation with regard to atoms near misfit nodes for Ni/Cu. The decreased misfit node spacing for Cu/Ag alternatively distributes the restructuring associated with plastic deformation over a larger percentage of atoms at the interface. Interface sliding facilitated by misfit dislocation motion is found to facilitate deformation extending into the bulk lattices centered on misfit nodes. The depth of penetration of those fields is found to be greater for Ni/Cu than for Cu/Ag. The study of dislocation plasticity mediated by semi-coherent interfaces can aid in the design of certain heterostructured materials, such as nanolaminates. The evolution of interface misfit patterns under complex stress fields arising from dislocation pileups can influence local dislocation/interface interactions, including effects of multiple incoming dislocations. This work utilizes the Concurrent Atomistic-Continuum modeling framework to probe the evolution of misfit structures at semi-coherent Ni/Cu and Cu/Ag interfaces impinged by dislocation pileups generated via nanoindentation. A continuum microrotation metric is computed at various stages of the indentation process and used to visualize the evolution of the interface misfit dislocation pattern. The stress state from approaching dislocations induces mixed contraction and expansion of misfit dislocation structures at the interface. A lower number of misfit nodes per unit interface area coincides with greater localized deformation with regard to atoms near misfit nodes for Ni/Cu. The decreased misfit node spacing for Cu/Ag alternatively distributes the restructuring associated with plastic deformation over a larger percentage of atoms at the interface. Interface sliding facilitated by misfit dislocation motion is found to facilitate deformation extending into the bulk lattices centered on misfit nodes. The depth of penetration of those fields is found to be greater for Ni/Cu than for Cu/Ag.