Relationship between microstructure, mechanical, and biological response in biomedical Ti–Nb–Cu alloys

Abstract

Titanium alloys are highly used in biomedical applications, especially structural ones, due to their mechanical properties and biocompatibility. However, they are susceptible to pathogenic bacterial infections, a long-lasting challenge of biomaterials exacerbated by the rise of antibiotic resistant bacteria. To address this, novel Ti–Nb–Cu alloys with intrinsic antibacterial capability were developed and characterised in this study. It is found that changing the amount of Nb and Cu brings about manufacturability and microstructural modifications. Specifically, the amount of porosity increases, the microstructure changes from lamellar to β type, and precipitation of the eutectoid Ti₂Cu intermetallic phase occurs as the contents of Nb and Cu increase. Accordingly, the Ti–Nb–Cu alloys become stronger and less ductile, though they do not fail catastrophically. They always form a protective passivation layer against corrosion, though the corrosion rate is composition dependent. They are characterised by a very strong antibacterial efficacy against both gram negative and gram positive bacteria, and they are not cytotoxic. This combination makes the developed Ti–Nb–Cu alloys promising candidates for structural biomedical applications.