Effect of pulse on-time and peak current density on pulse plated Re-Ni alloys

Rhenium (Re), with its unique chemical andmechanical properties, has sparked a rising interest inmany communities in recent years. Electrochemical deposition has proven to be a promising method for the manufacture of Re-based products, with pulse electrodeposition allowing for finer control of the deposit properties. In this work, the effects of a wide range of pulse-plating parameters on the composition and microstructure of Re-Ni alloys were studied. The samples were examined under a scanning electron microscope, and it was found that a nodular morphology was generated in all samples within the region of pulse parameters investigated. A surface morphology diagram was constructed, delineating the conditions leading to colonies that extend perpendicularly from the substrate vs. those that remain nearly flat on the substrate surface ('rough' vs. 'smooth' deposits, respectively). XPS analysis showed an increase in the rhenium oxide content relative to pure Re, both at higher on-times and at higher peak current densities. XRD analysis showed that all samples contained fcc Ni, although certain fcc Ni reflections were absent in the case of smooth samples. This absence was coupled with evidence of a solid solution of Re in an hcp Ni lattice, found exclusively in the smooth samples.