Microstructure and properties of CoCrFeNiSi_x high-entropy alloy coating by laser cladding

In order to investigate the effect of Si content on the microstructure and properties of CoCrFeNiSi_x (x=0.5, 1.0, 1.5) high-entropy alloy coating, the high-entropy alloy coating was prepared by laser cladding technology. The phase composition, microstructure, element distribution, hardness value, wear resistance and corrosion properties of the coating were characterized by X-ray diffraction, scanning electron microscopy (SEM), energy dispersive spectroscopy, microhardness tester, friction and wear tester, and electrochemical workstation. The results show that with the increase of Si content, the alloy phase changes from single-phase face-centered cubic structure to face-centered cubic structure, silicon compound (σ) phase structure, and finally form face-centered cubic structure, body-centered cubic structure and σ mixed structure. The microstructure of the coating mainly changes from columnar crystals to dendritic crystals and finally to cellular crystals. At the same time, the hardness of the coating also increases. When the Si content is 1.5, the average hardness of the coating reaches 619.04 HV0.2, which is about 2.67 times that of the substrate. The wear amount and friction coefficient of the coating decreased with the increase of Si content, and the wear resistance of the coating increased significantly. In 3.5%NaCl solution, the corrosion performance of the coating increases first and then decreases with the increase of Si content. When Si content is 1.0, the corrosion performance of the coating is optimal.