Influence of trace scandium addition on mechanical properties and biocompatibility of metastable β Ti–39Nb alloy for biomedical applications

Achieving low elastic modulus (that closes to human bone) and exceptional biocompatibility of Ti–Nb binary alloys cost-effectively through traditional methods remains a significant challenge, which needs to incorporate multiple alloying elements or complex processing techniques. The influence of the addition of 0.5 wt% scandium (Sc) on the microstructure, mechanical properties, and biocompatibility of metastable β type titanium Ti–39Nb (wt.%) were investigated in this work. Ti–39Nb-0.5Sc had an elastic modulus of 41.1 GPa (lower than Ti–39Nb, 51.9 GPa) and a tensile strength of 568.8 MPa (higher than Ti–39Nb, 510.5 MPa). The reduced elastic modulus by alloying Sc is attributed to the presence of nanoscale Sc oxides that suppressed martensite transformation and growth during quenching. Moreover, the addition of Sc significantly enhanced the biocompatibility of Ti–39Nb alloy in both in vitro and in vivo conditions via grain refinement, improving Ti–39Nb alloy surface hydrophilicity, thereby promoting the adhesion and proliferation of MG 63 osteoblast cells. The addition of Sc enhances the in vivo osseointegration capability due to lower elastic modulus, resulting in accelerated bone healing processes. These findings highlight the effectiveness of Sc addition in simultaneously optimizing the elastic modulus and biocompatibility of Ti–39Nb alloy, offering a simple approach for developing advanced implant materials.