Development and characterizations of low-modulus Ti–Nb–Cu alloys with enhanced antibacterial activities

Avoiding infection is a requirement for the long-term stability and safety of implants, but most Ti alloys for implantation hardly inhibit the bacterial proliferations. Cu works as a β stabilizer in Ti alloys, and Cu ion can kill bacteria. To obtain antibacterial activities in low-modulus Ti alloys, Ti–35Nb–(0, 1, 2, 3, 4)Cu (wt%) alloys were prepared by non-consumable arc melting following by homogenization, hot rolling, and solution treatment. They were then subjected to phase analysis, microstructure observation, tensile test and dynamic polarization. The cytotoxicity and antibacterial activities were finally evaluated. The results show that Cu stabilizes the β phase and inhibits the generation of α" phase during quenching. Ti–35 Nb and Ti–35Nb–1Cu consist of β and α" phases, and Ti–35Nb–(2, 3, 4)Cu alloys have a single β phase. The Ti–Nb–Cu alloys exhibit the Young's moduli ranging from 57 to 72 GPa. All the alloys show passivation behavior with a low passive current density. Cytotoxicity is hardly observed in the alloys. The antibacterial rates of Ti–35Nb–(1, 2, 3, 4)Cu alloys against E. coli are 62.8%, 68.9%, 70.9% and 73.2%, respectively, and the antibacterial rates against S. aureus are 63.4%, 69.7%, 72.8% and 74.7%, respectively. The developed β-type Ti–35Nb–4Cu alloy shows a relatively low Young's modulus and good antibacterial properties, and is a candidate for biomedical applications.