Coupled Structural Characteristics Boost Brazing Performance of Ti ₂ AlNb Alloy

Brazing of Ti 2 AlNb alloy is a pivotal technique for new generation aero‐engine lightweight structures, yet developing novel filler metal and achieving the extraordinary performance of titanium alloy brazed joints remains challenging. Here, this study designed an innovative filler metal (Ti 70 ‐ x Zr x Cu 15 Ni 15 ) and developed inspired coupled structural characters featuring coherent interface, microstructure refinement, and grain boundary migration, promoting the synergistic strengthening of joints. The highest shear strength and fracture toughness of Ti 2 AlNb brazed joints with Zr11 filler metal reached 438 MPa and 25.47 MPa m 1/2 . The joint strength via heat exposure and thermal cycling maintained 366.80 and 392.40 MPa, respectively. The perfectly continuous coherent relationships at the (Ti, Zr) 2 (Cu, Ni)/(Ti, Zr) 3 Al interface were revealed, which accelerated mobile dislocation emission without termination of dynamic equilibrium. First‐principles calculations suggested that the enhanced covalent nature of Ti‐Ti bonds raised the migration barrier of Ti atoms to 0.60 eV, inhibiting bond reconfiguration and facilitating significant microstructural refinement and anisotropy improvement. Furthermore, the interface between the β‐Ti of the brazing seam and Ti 2 AlNb base metal formed a remarkable grain boundary migration with Zr11 filler metal, preventing premature fracture via geometric interlocking. Molecular dynamics simulations revealed that the Ti 2 Ni/Ti 2 Ni model maintained an ordered atomic arrangement without strain localization up to 8.5% strain. This configuration outperformed the TiNi/Ti 2 Ni model, achieving a tensile strength of 17.2 GPa. Coupled structural characteristics developed herein were proven appealing in manufacturing high‐performance Ti 2 AlNb brazed joints and establishing a transferable strategy for brazing other titanium alloys.