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Although CoCrFeNi high-entropy alloy (HEA) exhibits excellent ductility due to its face-centered cubic (FCC) crystal structure, its relatively low strength limits its applicability in certain industrial applications. To enhance its bulk mechanical performance, alloying additions can be introduced, while various surface modification techniques can be employed to improve its surface properties. In this study, CoCrFeNi HEA was produced by vacuum arc melting, followed by homogenization at 1150 °C for 24 h. Zr additions ranging from 1 to 4 wt.% were introduced to promote grain refinement and improve bulk hardness. The addition of Zr resulted in a moderate increase in hardness, from approximately 150 HV to 250 HV. To further enhance surface properties, a low-temperature aluminizing treatment was carried out at 700 °C for 4 h. This process led to the formation of Co- and Ni-based aluminide intermetallic phases on the surface, resulting in a significant increase in hardness from 250 HV to approximately 700 HV. In addition to Vickers hardness testing, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were performed for structural and microstructural characterizations.
Keywords: HEA; CoCrFeNi; Aluminizing; Hardness; Coating; Alloying© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.