Oxygen-mediated high uniform plasticity in α-β titanium alloys.

Abstract

Titanium alloys are critically important materials, yet their development has long been constrained by a fundamental trade-off between yield strength and uniform elongation-a more challenging limitation than the conventional strength-ductility trade-off. Here, we present a dual strategy for α-β titanium alloys that transforms high oxygen from an embrittling liability into a powerful performance enabler. First, we leverage high oxygen ( ≥0.40%) to activate prominent pyramidal <c + a> slip in the α-phase. Second, we engineer a tailored α-β microstructure through alloy design (Ti-O-Fe), laser-based powder bed fusion, and annealing to enable sustained slip transfer across α-β interfaces. The resulting high-strength α-β alloys achieve record uniform elongations: Ti-0.45O-4Fe delivers ≥14% (total: ≥27%) at yield strengths ≥980 MPa, and Ti-0.5O-5Fe achieves ≥13% (total: ≥23%) at yield strengths ≥1075 MPa. This work simultaneously addresses the yield strength-uniform elongation trade-off and oxygen embrittlement, demonstrating a design paradigm for α-β titanium alloys.