Evading Strength–Ductility Trade‐Off in Titanium Matrix Composites via High‐Critical Resolved Shear Stress Dislocation Promotion and Grain Subdivision

ABSTRACT

The strength and ductility trade‐off in titanium matrix composites (TMCs) is a critical factor limiting their widespread application. In this study, a (TiB + TiC)/Ti–6Al–4V composite with an optimal balance between strength and ductility was engineered via multi‐directional forging. Compared to the matrix alloy, the ultimate tensile strength increased by 10.4% without reducing the plasticity (14.5%). The mechanisms for overcoming the strength–ductility trade‐off were systematically investigated. TiB promotes the activation of dislocations with high critical resolved shear stress (CRSS) and facilitates the activation of multiple slip systems. Meanwhile, a novel TiB‐mediated grain refinement mechanism during deformation is found: differences in dislocation motion among various regions within grains adjacent to TiB induce grain subdivision, thereby leading to grain refinement in the TiB‐surrounding region. Based on the aforementioned effects of TiB on the surrounding grains during deformation, the tailored multi‐pass multidirectional forging promotes extensive grain refinement during deformation. Moreover, it facilitates the refinement and dispersion of TiB, thereby enhancing the activation of multiple slip systems and coordinated deformation. The new discovery of the deformation mechanism of TiB on the surrounding grains provides valuable insights for evading the strength and ductility trade‐off.