Microstructure and strain in electrodeposited Cu/Ni multilayers

Abstract

Electrodeposited Cu/Ni multilayers with different modulation lengths Λ = 4–18 nm were examined by means of x-ray diffraction and transmission electron microscopy. Preferred orientations of [111], [110], and [001]-types, as determined from relative x-ray diffraction peak intensities, were seen in the multilayers. By means of computer simulations of the measured x-ray diffraction spectra, several parameters of the multilayers, such as Λ-values and fluctuations ΔΛ, as well as lattice strain, were determined. Multilayers having large Λ were found to be fully relaxed due to interfacial dislocation formation. In short Λ [001]-texture multilayers partial strain relaxation occurs, probably due to the incorporation of Cu into the Ni layers. Both of the processes lead to the diffuse Cu/Ni interfaces. Short wavelength multilayers with a [111]-preferred orientation were almost fully strained. The importance of the [111]-texture in the improvement of mechanical strength of Cu/Ni multilayers resulting from its enhanced ability for stain accommodation is discussed.