High-entropy Alloy Coating Deposition by Detonation Spraying Combined with Heat Treatment

In this work, feasibility tests of new two-stage approach of deposition of thick high-entropy alloy coatings were performed. At the first stage of this approach, metal composite coating is formed by detonation spraying of low-entropy metal powder blends. At the second stage, the composite precursor coating is heat treated in order to promote the synthesis of high-entropy phases. The tests were carried out using three different powder mixtures of Fe, Ni, Cu, Co, and Al powders. Experimental results showed that the detonation spraying allows formation of uniform metal composite coating. The microstructure analysis and microhardness measurements of the coating before and after heat treatments confirmed that the heat treatment enables element diffusion in the coating followed by formation of CoFeNi, CoCuFe0.8Ni, and Al0.05CoCu0.3FeNi alloys with uniform fcc structure after recrystallization. At the same time, the final composition of the coatings differed from the targeted ones due to different deposition efficiencies of the particles during detonation spraying process.