Influence of dilution rate on the microstructure and properties of FeCrCoNi high-entropy alloy coating

The influence of laser parameters and alloying elements on the dilution rate of FeCoCrNi coating was investigated. It was found that the alloying elements have more significant effect on the dilution rate than the laser cladding parameters. Optical microscopy, scanning electron microscopy, X-ray diffraction analysis, micro-hardness test, wear test, electrochemical corrosion test, and high-temperature oxidation test were conducted to study the influence of dilution rate on the microstructure and properties of the FexCoCrNi coatings. The results have shown that the transfer of Fe element from the substrate could make the mixed entropy of the Fe0CoCrNi coating close to the theoretical mixed entropy of the FeCoCrNi high-entropy alloy. Excess Fe element in the original powder increased the dilution rate, leading to a reduction in the mixed entropy of the coating. However, it did not lead to the generation of new phases in the coating. The atomic radius differences between the elements could lead to large lattice distortion in the FCC crystal lattice. The level of lattice distortion and micro-hardness of the FexCoCrNi coatings increased with increasing Fe element content. Furthermore, the excess Fe elements weakened the self-passivation ability and deteriorated the high-temperature oxidation resistance of the coating.