Ultrastrong and ductile hierarchical heterostructured titanium composites from room to high temperatures

Titanium matrix composites (TMCs) offer significant enhancements in strength and heat resistance while preserving the low-density characteristic of advanced lightweight titanium alloys. However, ultra-strong, high-temperature TMCs are typically brittle at room temperature. Here, we overcome this limitation reporting a novel hierarchical, heterostructured design that achieving a 9.5% ductility —exceeding that of the TA15 matrix alloy—along with a remarkable tensile strength of nearly 1.4 GPa at room temperature and 700 MPa at 600°C. This design forms hard, fine-grained regions homogeneously embedded within a soft, coarse-grained matrix. The hierarchical architecture facilitates the emergence of hetero-deformation-induced (HDI) stresses and strain partitioning, thereby enhancing strain hardening and dislocation activity. Our design strategy provides a pathway to achieving not only an optimal combination of strength-ductility at room-temperature but also exceptional high-temperature resistance. The TA15-Si-TiB composite exhibits a multi-scale heterogeneous structure consisting of hundred-micrometer-scale heterostructured grains and a continuous network of nanoscale precipitates ((Ti, Zr)5Si3). This interconnected architecture enables exceptional room-temperature ductility through its matrix behavior. Synergistic reinforcement by TiB whiskers and Si nanoprecipitates simultaneously achieves a strength-toughness synergy at room temperature and significantly enhanced elevated-temperature strength.