Ultra-strong and ductile low-alloy titanium by additive manufacturing

Strong yet ductile Ti alloys are crucial for aerospace and biomedical applications. While low-alloy Ti systems reduce dependence on expensive alloying elements, they often suffer from poor mechanical performance. We demonstrate the development of high-strength low-alloy (HSLA) Ti by leveraging the highly non-equilibrium processing conditions of additive manufacturing to control diffusive phase transformations. This approach enables the formation of hierarchical microstructures in Ti-Cu alloys, featuring micron-sized grains with refined laths and finely dispersed nanoprecipitates. The resulting structural hierarchy effectively impedes dislocation glide and promotes multislips, delivering ultra-high strength without compromising ductility. A Ti-5Cu alloy with dual nanoprecipitation achieves an exceptional ultimate tensile strength of 1,340 MPa and 12% elongation to failure, outperforming most commercial Ti alloys. These results highlight the transformative potential of additive manufacturing to develop more sustainable Ti systems that are strong, ductile, low-alloyed, and cost-effective.