Influence of WC addition on the microstructure and properties of AlCoCrFeNiCu high-entropy alloy coatings by plasma cladding

In this study, high-entropy alloy coatings of AlCoCrFeNiCu(WC)X were fabricated on 35CrMo steel using plasma cladding, with varying WC content (x = 0, 20, 40, 50, 60, and 70 wt%). The microstructure and phase composition of the coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron back-scattering diffraction (EBSD). The coatings were also analyzed for their microhardness, wear resistance and corrosion resistance. The results indicate that all coatings contain both FCC and BCC phases. With the addition of WC, W-rich carbide and Cr-rich carbide phases developed in the coatings, while a Cu-rich L12 phase coherently precipitated within the FCC phase. The incorporation of WC refined the coating grains, increased the geometrically necessary dislocation density (rho GND), and significantly enhanced both the microhardness and wear resistance of the coatings. Furthermore, the corrosion resistance of the coatings initially increased with the addition of WC but then decreased as WC content continued to rise. The coating with 40 wt% WC exhibited the optimal corrosion resistance.