## 4 Conclusions  
CuCrFeMnNi high-entropy alloy coatings, with 5 wt. %Cu and 10 wt. %Cu, were deposited on stainless steel substrates using the sputtering deposition method. Deposition parameters were studied in relation to the obtained layer thickness and quality. The composition of the obtained thin films is homogeneous and very close to the original composition of the alloys, with only minor concentration differences. The largest differences can be observed in the Mn and Ni distribution. The EDS analysis shows that the elements are uniformly distributed throughout the entire mass of the deposited film. The cross-sectional SEM analysis reveals that the samples exhibit a dense, uniform deposition \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Corrosion** & **Corrosion** & **Corrosion** & **Corrosion** & **Polarization** \\  & **Potential,** & **Current** & **Current** & **Rate** & **Resistance,** \\  & **Ecor\({}_{\text{Obs}}\)** & **Density, jcorr** & **Intensity,** & **(nm/Year)** & **R\({}_{\text{p}}\) (M\(\Omega\))** \\  & **(mV)** & **(nA/cm\({}^{2}\))** & **i\({}_{\text{corr}}\) (nA)** & **(nm/Year)** & **R\({}_{\text{p}}\) (M\(\Omega\))** \\ \hline \hline \multicolumn{6}{c}{**HEA Coatings**} \\ I8-6-C1 & \(-\)71.27 & 8.43 & 8.43 & 98 & 3,09 \\ I8-6-C2 & \(-\)21.22 & 7.90 & 7.90 & 91.8 & 3.29 \\ I8-6-C3 & 107.53 & 3.36 & 3.36 & 39 & 7.76 \\ I8-7-C1 & 113.52 & 7.07 & 7.07 & 82.2 & 3.68 \\ I8-7-C2 & 110.98 & 6.12 & 6.12 & 74.1 & 4.02 \\ I8-7-C3 & 73.64 & 0.832 & 0.832 & 9.67 & 31.31 \\ \multicolumn{6}{c}{**HEA ingots**} \\ I8-6-T & \(-\)78.91 & 35.9 & 35.9 & 418 & 0.72 \\ I8-7-T & \(-\)132.83 & 111 & 111 & 1290 & 0.23 \\ \multicolumn{6}{c}{**Stainless steel**} \\
304L & \(-\)199.47 & 102 & 102 & 1190 & 0.25 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Corrosion results for I8-6 and I8-7 coatings deposited at different power levels (200 W, 250 W and 300 W), I8-6 and I8-7 ingots, and 304L stainless steel in NaCl electrolyte. Figure 9: Corrosion results for I8-6 (**a**) and I8-7 (**b**) coatings in NaCl electrolyte, at various deposition parameters, presented against stainless steel values. with good adhesion to the substrate. The particle size is in the nanometer range. The coating thickness for both samples is approximately 1.5 \(\upmu\)m at 300 W. The deposition parameters had a slight influence on the thickness of the layer and overall quality, showing that a value of 300 W is generally optimal for various Cu contents. XRD analysis demonstrated the presence of FCC and BCC phases in as-cast Cu-Cr-Fe-Mn-Ni HEAs, while deposited HEA-based coatings exhibit nanocrystalline structure aligned to single-phase FCC solid solution. Crystalline growth was confirmed by AFM studies, which also showed roughness and grain size growth with an increase in the magnetron sputtering power. The scratch test method highlighted that the coating adheres well for both deposition materials on the 304L steel substrate. Electrochemical corrosion studies show that sample I8-7-C3, obtained from HEA ingots with 10% Cu, exhibits the lowest corrosion rate (9.67 nm/year) and the highest polarization resistance (31.31 M\(\Omega\)). The obtained coatings exhibit superior corrosion resistance compared to the alloys from which they were derived and demonstrate enhanced mechanical and corrosion properties relative to uncoated stainless steel samples. Conceptualization, A.S. and D.M. ; methodology, L.-F.M. and I.-A.T.; data curation, S.C., B.-A.S., L.-F.M. and L.-M.C. ; writing--original draft preparation, A.S., S.C., B.P., J.W., O.O., M.G. and N.V.; writing--review and editing, D.M., A.-C.M., J.W., O.O., M.G. and N.V.; visualization, A.-C.M., I.-A.T. and B.-A.S.; supervision, D.M., B.P. and A.P. ; project administration, A.P. and L.-M.C. All authors have read and agreed to the published version of the manuscript. This work was supported by project PNRR/2022/C9/MCID/I8, CF58/14.11.2022, contract no.