• • Au-catalysed C3T achieved near-zero wear and a stable COF of ~0.3 under a 20 N load, demonstrating superior tribological performance for high-load sliding contacts.
• • Ag-catalysed C3T delivered antibacterial efficacies of 99.878% against E. coli and 99.999% against S. aureus within 3–6 h of contact, via passive Ag-ion release, addressing infection risks in biomedical and marine applications.
• • Both treatments increased bulk tensile strength by ~50%, from 872±39 to 1,280±40 MPa, enhancing structural integrity without compromising surface functionality.
• • The IBTSF strategy integrates bulk heat treatment with surface functionalisation in a single step, offering a scalable and efficient route for multifunctionalising metastable β-titanium alloys.