Abstract:Dense and uniform high-entropy alloy AlCoCrFeNi gradient composite coating with different WC content was prepared on 45# steel substrate by laser cladding technology. The effect of ceramic particle content on the microstructure evolution and mechanical properties enhancement mechanism of high-entropy alloy gradient coating was quantitatively analyzed in order to improve the surface wear resistance of metal parts. The results show that with the increase in WC content, the grain size of the coating decreases from 20.16 μm to 7.71 μm, and the grain shape changes from cellular to dendrite and equiaxed. In addition, the microhardness of the gradient composite coating is significantly increased, which is 3 times that of the substrate, and 1.4 times higher than that of the high-entropy coating without adding WC. The coating mainly consists of body-centered cubic phase and metal carbide, and the corresponding diffraction peak intensity increases gradually with the increase in WC content. The wear performance test results show that the coating exhibits the best wear resistance when the WC content is 20wt%, and the friction coefficient and wear amount are 0.4680 and 0.16 mg, respectively, which are lower than the coating with 40%wt WC which has the highest average hardness, indicating that maintaining appropriate toughness while improving the hardness of the coating is the key to achieve the optimization of the coating performance. This study provides a certain reference value for the study of the optimization of high entropy alloy coatings prepared by laser cladding.