Dual-Array Nano Configuration for High-Performance Metastable β Titanium Alloys

Catastrophic failures in engineering metallics frequently occur at high temperatures. A fundamental understanding of plastic deformation and the mechanisms governing the strength-ductility trade-off is essential for developing titanium alloys exhibiting superior properties at elevated temperatures. Herein, a metastable β titanium alloy (Ti-15.1Mo-3.1Nb-2.77Al-0.21Si, wt.%) exhibits unexpected mechanical properties, including an ultimate tensile strength of 863 MPa and a total elongation of 78.3% at 500 °C, accompanied by a continuous and strong work hardening rate (2000-3100 MPa). Dislocation slip and heating play pivotal roles in interlaced parallel α nucleation, and thermal activation promotes interlaced α nucleation. Finally, the dual-array nano configuration of dense (≈68%) and thin (≈10 nm in width) α phase forms. Hierarchical microstructural evolutions, including β to α phase transformation, nano α grains with dual-array configurations (interleaved and parallel), and dislocation interaction, contribute to the excellent mechanical properties. These findings reveal that dynamic nano α precipitation with unique dual-array nano configurations can unveil new prospects for the development of high-performance metastable titanium alloys at elevated temperatures.