Novel Ti-Zr-Hf-Nb-Fe refractory high-entropy alloys for potential biomedical applications

In the present work, the TiZrHfNbFex (x = 0, 0.25, 0.5, 0.75, 1, 1.5, and 2, molar ratio) refractory high-entropy alloys (HEAs) were developed. The microstructure, mechanical properties, corrosion and wear resistance of the Ti-Zr-Hf-Nb-Fe HEAs were investigated. The Ti-Zr-Hf-Nb-Fe HEAs exhibited a dendrite structure with body-centered-cubic (BCC) + Laves phases. Among them, the TiZrHfNbFe0.5 HEA displayed good comprehensive mechanical properties with the hardness of 420 HV, compressive strength of 1450 MPa, and plastic strain of about 8%. In addition, the TiZrHfNbFe0.5 HEA possessed better corrosion resistance than that of the Ti6Al4V and the other Ti-Zr-Hf-Nb-Fe HEAs in phosphate buffer saline (PBS) solution, which might be related to the generation of more protective oxide films on its surface. Furthermore, the wear resistance of the Ti-Zr-Hf-Nb-Fe HEAs increased with the raise of the Fe content. The TiZrHfNbFe0.5 HEA demonstrated superior dry and wet wear resistance in comparison with the Ti6Al4V alloy. Therefore, the good mechanical properties, high corrosion, and wear resistance, the biocompatible constituent elements, as well as the low cost of the Fe addition render the Ti-Zr-Hf-Nb-Fe HEAs as promising candidates as biomedical-implantation materials.