Chuanxi Ren, Hao Wang, Xiangyuan Cui, Jinjin Guo, Hansheng Chen, Zizheng Song, Hengchao Shi, Yating Ran, Chunjin Wang, Chi Yuen Cheung, Hongwei Liu, Kang Cheung Chan, Xiaozhou Liao, Ting Zhu, Dengke Chen, Simon P. Ringer, Zibin Chen
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.