Effects of misfit dislocations on the mechanical properties of Cu/Ni multilayers

The nanoindentation on Cu-Ni thin films was simulated by using 2D molecular dynamics simulations(MDS), and the effects of the misfit dislocations on the mechanical properties of the multilayers was examined.The misfit dislocation network plays an important role in strength enhancement of Cu/Ni multilayers because of its resistant to glide dislocations.But the strengthening relies on the wavelength,which was defined as the thickness of adjacent two layers in multilayers.When the wavelength was bigger than the critical value λ_c, the stress field of misfit dislocation was independent on the wavelength.When the wavelength was less than the critical value λ_c, the stress concentration caused by the movement of misfit dislocations will weaken Cu/Ni multilayers. And the critical wavelength should be bigger than the depth where dislocation nucleates in the inner part of one layer.