Surface engineering of CoCrFeNiZrx (x = 0.1, 0.3, and 0.5) high-entropy alloys by laser remelting: Towards enhanced hardness and wear resistance

: Laser remelting (LR) technology was employed to modify the surface of CoCrFeNiZr x (x = 0.1, 0.3, and 0.5) high-entropy alloys (HEAs) prepared by vacuum arc melting. XRD analysis revealed that the as-cast CoCrFeNiZr x alloys consisted of both Face-Centered Cubic (FCC) and Laves phases. With increasing Zr content, the Zr 0.5 alloy developed a typical FCC + Laves eutectic structure. LR treatment refined the grain structure and promoted a more homogeneous elemental distribution, thereby effectively alleviating elemental segregation. The hardness of the alloys increased markedly with increasing Zr content, reaching 446.44 HV for Zr 0.5 . After LR treatment, the hardness further increased to 529.78 HV. The friction coefficient of the as-cast alloys decreased from 0.35 to 0.17 with increasing Zr content. LR treatment significantly reduced the wear rate, and the LR-Zr 0.5 alloy exhibited the best wear resistance. Moreover, the wear mechanism changed from abrasive wear and adhesive wear to abrasive wear and oxidative wear. Electrochemical corrosion tests indicated that increasing Zr content deteriorated the corrosion resistance of the alloys, as evidenced by an increase in I corr from 7.47 to 10.27 μA·cm −2 . In contrast, LR treatment improved the corrosion performance, with LR-Zr 0.1 exhibiting the best corrosion resistance, which was mainly attributed to grain refinement and the homogenization of elemental distribution. Overall, LR technology effectively optimized the microstructure and surface properties of CoCrFeNiZr x HEAs, significantly enhancing their hardness, wear resistance, and corrosion resistance. These findings provide both theoretical and experimental support for the surface engineering of HEAs.