Evolution of texture in electrodeposited Ni/Cu layered nanostructures

The objective of this research was to study the evolution of crystallographic texture in electrodeposited Ni/Cu laminated nanostructures. Thick films (14-40 µm) consisting of nickel and copper nanolayers (7-27 nm) were fabricated on annealed polycrystalline copper substrates using an electodeposition technique. The microstructure of the deposits was varied by changing the deposition time of each layer and the electrolyte temperature. X-ray diffraction, transmission electron microscopy and scanning electron microscopy were applied to characterize the deposits. Three microstructural behaviours were observed. The deposit with a very fine bilayer thickness (7 nm) was composed of coherent layers parallel to the substrate surface. This deposit replicated the cube orientation of the substrate and showed a strong ⟨100⟩ texture throughout the thickness of the deposit. An increase in the bilayer thickness (17 and 27 nm) caused a change in the texture from ⟨100⟩ on the substrate side to ⟨111⟩ on the solution side. This change in texture is suggested to be associated with a change in the deposition front orientation from {100} to {110} and the subsequent twinning of the cube-oriented crystals. A decrease in the electrolyte temperature inhibited faceting of the interface and hence no twinning was observed.