Ti–Zr–Hf–Nb–Ta–Sn high-entropy alloys with good properties as potential biomaterials

(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)_100-xSn_x (x = 3, 5, and 7; at%) high-entropy alloys (HEAs) with good mechanical properties, corrosion resistance, and biocompatibility were developed as potential biomaterials. The effects of Sn additions on the microstructure and properties of the HEAs were investigated. The (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)_100-xSn_x with x = 3 at% exhibited the single body-centered-cubic (BCC) structure. The HEAs with the further increased Sn contents of x = 5 at% and 7 at% were composed of a BCC phase and a hexagonal-close-packed (HCP)-(Sn, Zr) ordered phase. The addition of Sn improved the compressive yield strengths and hardness of the HEAs to 1068–1259 MPa and HV 315–HV 390, respectively. These HEAs also possessed relatively low Young’s moduli of 80–91 GPa. Among the present Ti–Zr–Hf–Nb–Ta–Sn HEAs, the (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)₉₇Sn₃ HEA exhibited the good combination of high yield strength of ~ 1068 MPa, relatively low Young’s modulus of 80 GPa, and good plasticity (~ 45%). The HEAs also possess good bio-corrosion resistance and biocompatibility, parallel to the Ti–6Al–4V alloy. The Ti–Zr–Hf–Nb–Ta–Sn HEAs with the integration of the high yield strength, relatively low Young’s modulus, and good corrosion resistance and biocompatibility are promising for biomedical applications.