Atomistic simulation of deformation induced rotation in Cu-Nb composites

Abstract

Accumulative roll bonding (ARB) of three copper-niobium (Cu-Nb) nano-composite models is simulated using molecular statics techniques to assess the rotational stability of Cu-Nb interfaces at high strains up to 90% thickness reduction. Crystals strain and rotate under compression, and certain Cu-Nb composites have been shown to reach a steady state of rotation at large rolling reductions. These steady-state rotations correspond to the formation of a preferred interface character between layers. Cumulative rotation of Cu and Nb layers was tracked as a function of strain using a rotation algorithm. A Cu-Nb bicrystal and poly-crystalline model with a {111}<110> Cu// {110}<111> Nb interface character were found to rotate significantly from their initial crystallographic orientation under compression. A Cu-Nb bi-crystal model with a {112}<111>Cu // {112}<110>Nb interface character was found to rotate less when rolled in the transverse direction compared to the typical <111>Cu//<110>Nb rolling direction. Results show that experimentally observed plastic stability of rolled Cu-Nb composites comes from a factor not accounted for in the simulation, like thermally activated dislocation mechanisms. The study refines the current knowledge of plastic stability in Cu-Nb composites.