Microstructure, mechanical properties, and corrosion resistance of biomedical Ti-Zn alloys prepared by spark plasma sintering

Dense Ti-Zn alloys with high strength and low elastic modulus were prepared by spark plasma sintering (SPS) for biomedical applications. The effect of Zn contents (5–20 wt%) on the microstructure, mechanical properties, wear resistance, and corrosion resistance of the Ti-Zn alloys were systematically investigated. The results show that the Ti-Zn alloys are mainly composed of α-Ti and Ti₂Zn phases with small amounts of β-Ti phase, and the quantity and size of the Ti₂Zn phase increase with increasing the Zn contents. The Ti₂Zn and α-Ti forms typical pearlite structures. Solid solution strengthening of Zn and the second phase strengthening of the Ti₂Zn result in a significant increase in mechanical strength, microhardness, and wear resistance of the Ti-Zn alloys. The Ti-Zn alloys exhibit peak values for both yield strength and microhardness when the Zn content is 15 wt%. Meanwhile, as the Zn content rises, the compressive strength progressively increases, whereas the fracture strain gradually diminishes. The fracture mechanism changes from the tough-brittle mixed fracture to the quasi-cleavage fracture and then to the cleavage fracture. The compressive elastic modulus of the Ti-Zn alloys ranges from 20 to 30 GPa, very close to that of the human bone. The wear resistance of the Ti-Zn alloys steadily enhances as the Zn content increases, and the wear mechanism changes from abrasive wear to adhesive wear and oxidative wear. Specifically, the wear rate of the Ti-20Zn shows an 86.7 % enhancement compared to pure titanium. The Ti-Zn alloys demonstrate a strong passivation capability in SBF solution, exhibiting outstanding corrosion resistance, while the increase of the Zn content has a certain negative effect on the corrosion resistance.