Mechanical, corrosion, and wear properties of biomedical Ti–Zr–Nb–Ta–Mo high entropy alloys

Abstract The microstructures, mechanical, corrosion, and wear behaviors of the TixZrNbTaMo (x = 0.5, 1, 1.5, and 2, molar ratio) high entropy alloys (HEAs) were studied. It was found that the Ti–Zr–Nb–Ta–Mo HEAs showed a dendrite structure with two body-centered-cubic (BCC) solid solution phases. The Ti0.5ZrNbTaMo HEA exhibited a high hardness of about 500 HV, high compressive strength approaching 2,600 MPa, and large plastic strain of over 30%. Furthermore, the highly-protective oxide films formed on the surface of Ti–Zr–Nb–Ta–Mo HEAs in the phosphate buffer saline (PBS) solution, which resulted in the high corrosion resistance of the HEAs. The Ti–Zr–Nb–Ta–Mo HEAs exhibited the greater dry- and wet-wear resistance than that of the traditional biomedical Ti6Al4V alloy. The results also indicated that with the decrease in the Ti content, the wear resistance of the Ti–Zr–Nb–Ta–Mo HEAs in the PBS solution improved. Finally, the Ti0.5ZrNbTaMo alloy presented the highest corrosive wear resistance among the four HEAs owing to its combination of good mechanical properties and high chemical stability.