Electrodeposited CoFeNi MEA coating on a Cu substrate from chlorides solution with enhanced corrosion resistance

This dataset contains the results of structure and corrosion resistance of electrodeposited CoFeNi medium-entropy alloy (MEA) coating on a copper substrate. The structural data include X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) results that confirm the presence of face-centered cubic (FCC) phase and nanocrystalline structure. The results of scanning electron microscopy (SEM) studies contain the images of coating surface in the back-scattered electrons (BSE) mode and the energy dispersive X-ray spectroscopy (EDX) maps of chemical elements distribution. The dataset contains also SEM images and atomic force microscope (AFM) surface topography analysis of the copper substrate after degreasing and etching before electrodeposition. The electrochemical results confirm the enhanced corrosion resistance of the MEA coating in a 3.5% NaCl environment at 25 °C. The dataset includes the results of open-circuit potential in a function of time (1800s) and polarization resistance curves for the copper substrate and the sample with MEA coating.Sample preparation:Substrate material: copper plate with dimensions of 50 × 50 × 0.5 mm degreased in a solution of NaOH (25 g/L), Na2CO3 (25 g/L), and Na3PO4 (25 g/L) and then etched in a solution of H2SO4 (100 mL/L), HNO3 (30 mL/L), and HCl (10 mL/L). Each time after degreasing and etching, the plate was rinsed in distilled water.Coating: the electrodeposition process was performed in the aqueous solution of FeCl2 ∙ 4H2O (8.11 g/L), CoCl2 ∙ 6H2O (7.138 g/L), NiCl2 ∙ 6H2O (14.262 g/L), and H3BO3 (15 g/L) with graphite anode with dimensions of 120 × 44 × 4 mm. The process was carried out at a current of 0.5 A for 30 min using PPH-1503 (GW Instek) laboratory power supply at a temperature of about 30 °C. Experimental techniques:X-ray diffraction (XRD)- D8 Discover diffractometer (Bruker) (Co Kα, λ = 1.79 Å)Scanning electron microscopy (SEM)- Phenom ProX (Phenom World)Atomic force microscopy (AFM)- XE-100 (Park System)Transmission electron microscopy (TEM)- S/TEM TITAN 80–300 (FEI Company)Electrochemical tests- potentiodynamic method- Autolab 302N (Metrohm)Funding: The work was supported by the National Science Centre of Poland under decision no. 2024/08/X/ST11/01775.