Low-cost Ti alloys: assessment of their microstructure, mechanical properties, corrosion behaviour, and biological response

Orthopaedic and dental implants, the majority of which are made from titanium alloys, face the crucial challenge of both inducing osteogenesis whilst inhibiting bacterial biofilm formation in an economical manner over the life of the implant. This study introduces an innovative strategy combining cost-effective alloying elements, selected due to their reported biological benefits, for developing new titanium alloys that achieve a tailorable mechanical, corrosion, and biological response. The combination of alloying and manufacturing results in homogeneous materials characterised by a lamellar microstructure. The developed low-cost Ti alloys have a maximum ultimate compression strength of 659 MPa, maximum tensile yield stress of 606 MPa, and maximum elongation of 8.3% without failing catastrophically. The alloys do not degrade as abiotic corrosion is significantly hampered by their intrinsic passivation behaviour (maximum corrosion rate of 8.9 μm/year), and have adjustable surface wettability with contact angles in the 60-81° range. Consequently, stomal cell attachment, cytotoxicity and cytokine production (IL-6 and TGF-β1), and antibacterial rate on S. aureus are consistent and comparable to those of current implnat materials. Based on these characteristics, the low-cost Ti alloys are promising materials for load-bearing biomedical devices.