Development of Ti–Mo–Cu alloys with enhanced antibacterial activity for biomedical application

To advance the performance of Ti alloys for biomedical applications, Cu—a β-stabilizing element—was incorporated into a Ti–Mo alloy to synergistically achieve desirable mechanical properties and enhanced antibacterial activity. Ti–6Mo–(0, 1, 3, 5, 7)Cu ingots were fabricated via high-vacuum non-consumable arc melting, followed by homogenization treatment and hot rolling into sheets. Specimens for characterization and testing were cut from the sheets and subsequently solution-treated. Phase composition was analyzed using X-ray diffraction, and microstructure was observed by optical microscopy and transmission electron microscopy. Mechanical properties were determined via conventional tensile test, while superelasticity was evaluated through cyclic loading-unloading test. Corrosion resistance was assessed by potentiodynamic polarization measurement, and antibacterial activity was investigated using E. coli and S. aureus as the test strains, with commercially pure Ti serving as the control group. The results demonstrate that Cu addition enhances β-phase stability, inducing a phase composition shift from α'- and α''-phases to a dominant β-phase. Stress-induced martensitic transformation was observed in the Ti–6Mo–7Cu alloy, which exhibited a superelastic recovery rate of up to 2.4%. All Ti–Mo–Cu alloys displayed self-passivation behavior, with a passivation current density below 12.00 µA·cm⁻². The released Cu²⁺ concentration was approximately 6.94 µg·L⁻¹ after 24 h of immersion in PBS, while it reached ~23.44 µg·L⁻¹ after 168 h of immersion—meeting the biosafety requirements. Antibacterial efficiency was greatly improved with increasing Cu content. Specifically, the Ti–6Mo–7Cu alloy achieved antibacterial rates of 90.6% and 79.8% against E. coli and S. aureus , respectively, making it a promising candidate for biomedical applications.