| Summary: | Cavitation corrosion resistant coatings are an excellent solution to the cavitation corrosion problem. High entropy alloys provide a new possibility for cavitation resistant coatings due to their excellent comprehensive performance. Laser cladding was employed to synthesize AlCoCr<i><sub>x</sub></i>CuFe (<i>x</i> represents the Cr concentration, <i>x</i> = 0.5, 1.0, 1.5, 2.0) high entropy alloy coatings (HECs) on AISI 304 steel. The phase transformation, microstructure, micro-mechanical properties, and cavitation erosion performance of HECs were studied. Results showed that AlCoCr<i><sub>x</sub></i>CuFe HECs were composed of BCC and FCC duplex phase. The microstructure of HECs showed a typical dendritic structure. The composition segregation of interdendrite structures was observed. Cavitation erosion resistance represented by 20 h volume loss was decreased with the increase in Cr content. AlCoCr<i><sub>x</sub></i>CuFe HECs with the lowest chromium content (AlCoCr<sub>0.5</sub>CuFe) showed the best cavitation erosion resistance among all samples. The cavitation resistance of AlCoCr<i><sub>x</sub></i>CuFe HECs has good correlation with the mechanical parameter <inline-formula><math display="inline"><semantics><mrow><msub><mi>H</mi><mi mathvariant="normal">n</mi></msub><msup><mrow></mrow><mn>3</mn></msup></mrow></semantics></math></inline-formula>/<inline-formula><math display="inline"><semantics><mrow><msub><mi>E</mi><mi mathvariant="normal">r</mi></msub><msup><mrow></mrow><mn>2</mn></msup><mo> </mo></mrow></semantics></math></inline-formula>(<inline-formula><math display="inline"><semantics><mrow><msub><mi>H</mi><mi mathvariant="normal">n</mi></msub></mrow></semantics></math></inline-formula> is nanohardness, <inline-formula><math display="inline"><semantics><mrow><msub><mi>E</mi><mi mathvariant="normal">r</mi></msub></mrow></semantics></math></inline-formula> is elastic modulus) and phase formation parameter δ (δ is atomic radius difference). The surface after 20 h of cavitation erosion testing exposed the dendritic structure of BCC phase, which was caused by the destruction of the interdendrite structure by cavitation impact.
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