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A Review on High-Entropy Alloys Coatings Fabricated by Electrodeposition: The Correlation Between Composition, Properties and Processing Parameters
This work provides an overview on the fabrication process, composition and properties of high-entropy alloy (HEA) coatings fabricated by electrodeposition. Special attention is paid to the effect of electrodeposition parameters and electrolyte composition on the microstructure, morphology, and mechanical/functional properties of the HEA coatings. It is demonstrated that the majority of researches has been focused on fabricating CoCrFeMnNi- and AlCrFeMnNi-based HEAs, with the addition of a few other elements by galvanostatic and potentiostatic techniques using both direct and pulsed current deposition modes. The fabricated HEA coatings exhibited different microstructures ranging from amorphous to nanocrystalline structures, exhibiting interesting magnetic, catalytic, and mechanical properties. Furthermore, we show that, while the possibility of fabricating metal matrix nanocomposite coatings using electrodeposition has been demonstrated, the fabricated composite coatings are mainly limited to transition element-based HEAs reinforced by graphene oxide and carbon nanotubes. Finally, several new directions and potential challenges such as electrochemical deposition of refractory HEAs and metal matrix composites reinforced by HEAs or high-entropy ceramics, as well as theoretical aspects of electrodeposition of HEAs and introducing machine learning to speed up the fabrication of novel coatings and optimize the processing parameters, are discussed.