Material Characterization of Electrodeposited Copper-Nickel Nanolaminated Alloy by SEM, EDS, and XRD

Abstract

Electrodeposited nanolaminated copper-nickel alloys (Cu-Ni) exhibit excellent mechanical properties due to their modulated structure and nanocrystalline microstructure. X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used to characterize the composition, grain size, phases, and laminate structure of a nanolaminated deposit to explore structure-process-property relationships. The processing method of interest was pulse current electrodeposition of Cu-Ni a rotating disk electrode (RDE) with increased rotation speed during deposition of Cu-rich layers. Although copper content was enhanced in this way, it also caused macroscopic swirls in the deposit's surface, which were reflected microstructurally as Cu-rich streaks, non-planar layers, and other inhomogeneous morphology in the nanolaminate coating. Bulk composition of the nanolaminate was calculated from XRD spectra as being over 67wt%Ni overall, with over 91wt% Ni in Ni-rich layers and over 43wt% Ni in Cu-rich layers. EDS data of the same deposit differed significantly from these values, suggesting an overall composition closer to 55 wt% Ni, with a Ni-rich layer composition of 81 wt% Ni and 8.4 wt% Ni in the Cu-rich layers. Grain sizes of 15.8-22.3 nm were calculated for the nanolaminated deposit compared to 13-19 nm grains in a monolithic Ni-rich deposit of Cu-Ni.