Interface-engineered titanium matrix composites with silicon-segregated boundaries for high-temperature strength-ductility synergy

High-temperature titanium alloys are approaching intrinsic performance limits, while discontinuous TiB whisker-reinforced composites provide a possible route to higher service temperatures. The central challenge is to improve strength without sacrificing ductility, especially because deformation and fracture are strongly governed by reinforcement interfaces. Here, a hot-extruded TiB/Ti65 composite is developed with ultimate tensile strengths of 1342 MPa at room temperature and 570 MPa at 800 °C. The composite also retains 21.5% ductility at 800 °C, showing a superior strength and ductility combination compared with most reported high-temperature titanium materials. By combining three-dimensional tomography, atomic-resolution microscope, in-situ micromechanical testing, and first-principles calculations, we reveal a Si-segregated TiB/α-Ti interface with enhanced adhesion work. This interface strengthens load transfer to aligned TiB whiskers and promotes pyramidal 〈c+a〉 slip in adjacent α-Ti, thereby improving local deformation compatibility. As a result, interfacial decohesion is suppressed, and ductile fracture is maintained at elevated temperature. These results demonstrate that atomic-scale chemical tailoring of reinforcement interfaces is an effective strategy for overcoming the strength and ductility trade-off in titanium matrix composites designed for extreme environments.