Exceptional strength–ductility–modulus combination in additively manufactured metastable β titanium alloy via synergistic tuning of strengthening mechanisms

Achieving high strength, low elastic modulus, and excellent ductility simultaneously remains a challenge for additively manufactured biomedical β titanium alloys. In this work, a novel Ti-14Nb-6Zr-3Fe-3Sn-0.65O metastable β titanium alloy was developed. By tuning solid solution and precipitation strengthening through Sn and O additions, the alloy achieves an outstanding combination of yield strength (1217 MPa), elastic modulus (67 GPa), and elongation (13%). The addition of Sn effectively refines the grain size and suppresses the precipitation of the ω phase, while also mitigating the effect of O on ω phase formation. The high strength originates from both solid solution strengthening (561 MPa) and precipitation strengthening (268 MPa). EBSD and TEM results reveal that the synergistic operation of multiple slip systems, frequent cross-slip, and effective slip transfer across grain boundaries are responsible for the alloy's excellent ductility. This work demonstrates that controlling the relative contributions of solid solution and precipitation strengthening offers a promising strategy for designing high performance β titanium alloys.