High-Performance Ti-CuO Composites with Strength-Ductility Synergy Via In-Situ Titaniothermic Reaction and Construction of Dual Heterogeneous Structure

Traditional single-element doping fails to break the strength-ductility trade-off and oxygen (O) tolerance limit of titanium (Ti) matrix composites (TMCs). Herein, low-cost copper oxide (CuO) was used as a Cu/O dual-source dopant to co-introduce copper (Cu) and O into pure Ti. Ti-CuO composites were fabricated via fast hot pressing (FHP)-hot rolling (HR) without extra heat treatment. During in-situ titaniothermic reaction, a dual heterogeneous structure formed, comprising soft α-Ti (equiaxed αₚ and lamellar αₛ) and hard Ti 2 Cu precipitates. O exists as interstitial solid solution in Ti matrix, while most Cu precipitates as lamellar Ti 2 Cu with low-misfit coherent interface (lattice misfit < 0.05). Tests reveal Ti-2.0CuO exhibits optimal properties: ultimate tensile strength (UTS) 1274±4 MPa and elongation (EI) 11.5±0.4%, achieving superior strength-ductility balance. High strength stems from synergistic O-induced solid solution strengthening, Ti 2 Cu precipitation strengthening, and heterogeneous deformation-induced (HDI) strain hardening. Excellent ductility benefits from the activation of pyramidal <c + a> slip driven by the O-regulated lattice c/a ratio and local stress concentration. This study provides a novel, scalable strategy for high-performance TMCs via integrating in-situ reaction, heterogeneous structure, and multi-mechanism synergy. • A low-cost CuO dual-source doping strategy is proposed, which breaks the strength-ductility trade-off and oxygen tolerance limit of TMCs from single-element doping, realizing precise elemental distribution control with O in interstitial solid solution and Cu precipitated as coherent Ti 2 Cu phases (lattice misfit < 0.05) in Ti matrix. • An integrated FHP-HR fabrication process without additional heat treatment is developed, which constructs a dual heterogeneous structure of soft bimodal α-Ti (equiaxed αₚ + lamellar αₛ) and hard Ti 2 Cu precipitates via in-situ titaniothermic reaction to achieve full densification, featuring simplicity, scalability and martensite phase avoidance. • The Ti-2.0CuO composite achieves excellent strength-ductility synergy (UTS: 1274±4 MPa, EI: 11.5±0.4%), with its strength doubled compared with pure Ti and ~300 MPa higher than Ti-1.6Cu, showing a superior strength-ductility balance to reported TMCs. • The core mechanism of strength-ductility synergy is elucidated: ultrahigh strength comes from the triple synergy of O-induced solid solution strengthening, Ti 2 Cu precipitation strengthening and HDI strain hardening; excellent ductility is realized by pyramidal <c + a> slip activation driven by O-regulated lattice c/a ratio and local stress concentration, which breaks the embrittlement bottleneck of high-O Ti-based materials. • A new design paradigm of in-situ reaction-heterogeneous structure construction-multi-mechanism synergy for high-performance TMCs is established, providing novel theoretical and technical support for the composition-structure-performance precision regulation of high-O-tolerance Ti-based materials with significant scientific value and engineering application potential.