Microstructural vortex formation during cyclic sliding of Cu/Au multilayers

Cu/Au multilayers with individual layer thickness of 100 nm were deformed by cyclic sliding using a nanoindenter. With increasing cycle number, a distinct sequence of changes was observed, from uniform thinning through formation of waviness and vortices until finally a mechanically mixed structure developed. Fluid-like behavior is observed and gradients of strain and strain rate are suggested to initiate the evolution of vortices driving the mechanical mixing of the layers.