Effect of frequency changes in pulsed deposition process on the composition and morphology of CoCrFeMnNi high entropy alloy coatings

In this study, the effect of frequency changes from 2500 to 5000 Hz in a %60 constant duty cycle on the composition and surface morphology of CoCrFeMnNi thin film alloy coating surface, synthesized by pulsed electrochemical deposition method, was investigated. Alloy coatings were obtained from chloride bath with organic solvent dimethylformamide (N, N-dimethylformamide) and acetonitrile on a Cu substrate. Microstructure changes, chemical composition and morphology of the coatings were investigated by thin-layer X-ray diffraction (GXRD), X-ray energy diffraction (EDS) and scanning electron microscopy (SEM), respectively. The results of EDS analysis showed that all the elements were successfully deposited on the copper substrate and the chemical composition changed by changing the applied frequency (2500 to 5000 Hz) at a %60 constant duty cycle; in both cases the mixing entropy was about 12 J/K.mol, in the range of high entropy alloy formation. The results of GXRD analysis confirmed the formation of FCC single phase solid solution structure. At the surface of the coating created at a frequency of 2500 Hz, the particles were spherical and agglomerated and the size of the crystallite was calculated at about 217 nm. The morphology of the deposited coat at 5000 Hz has cracks and hydrogen blisters as well as spherical particles on the surface, and the crystallite size was measured at about 109 nm.