High entropy alloys (HEAs) are commonly defined as alloys composed of five or more alloying elements. There are many different high entropy alloys with unique properties. The production of the high entropy alloys has been carried out in two types of bulk and coatings. Up to now most of the high-entropy alloys have been produced as a bulk material and less researches have been done on the production of these alloys as coatings. One of the less used methods and cost effective one for producing high entropy alloys coatings would be the electrochemical deposition techniques. In the present research, the CoCrFeMnNi high entropy alloys have been produced using the potentiostatic and pulse potential deposition methods in a chloride bath with DMF-CH3CN as a solvent. The effect of applied potentials of 4, 5 and 6 volts in potentiostatic method and frequencies of applied pulse potentials of 2500 and 5000 Hz and duty cycles of 50 and 60% on the formation of high entropy alloys with FCC solid solution structure, their composition, and morphology, wettability and corrosion resistance have been investigated. The microstructure and chemical composition have been studied using grazing X-ray diffraction (GXRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) have been used for investigating the corrosion behavior of the resulting HEAs. The EDS analysis revealed that change of electrodeposition parameters result in change of the HEAs chemical composition but in all cases, the entropy of mixing was about 12 JK -1 mol -1 that was in the range of high entropy alloys formation. The GXRD analysis proved the formation of a solid solution structure with the simple FCC structure. The morphology of the HEA coatings produced in a constant potential was flat, compact and without any crack, while it was rough, having semi-spherical prominences in HEA coatings produced using pulse technique. The results of the wettability tests have been revealed that in all cases the wettability angle was less than 56 degrees, and therefore the HEA coatings produced in all cases were hydrophilic. Finally, the investigation of the corrosion resistance properties of the coatings has been shown that the coatings produced at constant potential of 5 volts and the one coated at 2500 Hz with a 60% duty cycle have the corrosion densities of 0.0525 and 0.67 ?A/cm 2 , respectively, having the highest corrosion resistance in 3.5% NaCl solution. Using HEA coatings has a remarkable improvement in the properties of corrosion resistance compared to similar alloys. Using the HEA coatings of CoCrFeMnNi under optimal conditions could improve the corrosion resistance of the copper substrate in the order of 44. Keywords: 1. High entropy alloys. 2. Solid solution. 3. Corrosion. 4. Electrochemical electrodeposition.
