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High entropy alloys (HEAs), unlike conventional alloy systems, have attracted growing attention due to their unique combination of structural and functional properties arising from their multi-principal element design. In recent years, Bio-HEAs, composed of elements with proven biocompatibility, have emerged as promising candidates for biomedical applications. In this study, four equiatomic HEAs (TiNbTaZr, TiNbTaZrMo, TiNbTaZrHf, and TiNbTaZrV) were produced using vacuum arc melting. The structural characteristics of the HEAs were analyzed by X-ray diffraction (XRD), while their microstructures were examined via scanning electron microscopy (SEM). Elemental distributions within the microstructures were investigated using energy dispersive X-ray spectroscopy (EDS). Mechanical behavior was assessed through Vickers hardness testing, which revealed a clear correlation between alloying elements, structure, and hardness. Among the HEAs, TiNbTaZrMo exhibited the highest hardness value of 516±2.65 HV, whereas the base alloy, TiNbTaZr, showed a hardness of 323.6±5.18 HV. The additions of V and Hf resulted in hardness values of 410.2±4.27 HV and 316.2±4.66 HV, respectively. XRD analysis indicated the presence of dual BCC phases in the Mo- and V-containing alloys, while a single BCC phase was observed in the base and Hf-containing HEAs. Microstructural analysis revealed two distinct phase regions: Ta-rich and Zr-rich domains. These findings highlight the significant influence of alloying element selection on phase evolution and mechanical performance, demonstrating the potential for tailoring bio-HEAs for specific biomedical applications.
Keywords: Biological high entropy alloys, hardness, microstructure© 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.