Lean design of a strong and ductile dual-phase titanium-oxygen alloy

Unalloyed titanium boasts an impressive combination of ductility, biocompatibility and corrosion resistance. However, its strength properties are moderate, which constrains its use in demanding structural applications. Traditional alloying methods used to strengthen titanium often compromise ductility and tend to be costly and energy intensive. Here we present a lean alloy design approach to create a strong and ductile dual-phase titanium-oxygen alloy. By embedding a coherent nanoscale allotropic face-centred cubic titanium phase into the hexagonal close-packed titanium matrix, we significantly enhance strength while preserving substantial ductility. This hexagonal-close-packed/face-centred-cubic dual-phase titanium-oxygen alloy is created by leveraging the tailored oxide-layer thickness of the powders and the rapid cooling inherent in laser-based powder bed fusion. The as-printed Ti-0.67 wt% O alloy exhibits an ultimate tensile strength of 1,119.3 ± 29.2 MPa and a ductility of 23.3 ± 1.9%. Our strategy of incorporating a coherent nanoscale allotropic phase offers a promising pathway to developing high-performance, cost-effective and sustainable lean alloys.