Synergistic Enhancement of Strength and Creep Resistance in Additive Manufacturing Ti-6.5Al-2Zr-Mo-V Alloy via In Situ Co-Modification With Si and Y Elements

The demand for advanced aerospace components necessitates near-α titanium alloys with enhanced high-temperature performance and compatibility with additive manufacturing (AM). To address this, an in situ alloying strategy was employed to co-modify a Ti-6.5Al-2Zr-Mo-V alloy with Si and Y during laser powder bed fusion. The added elements effectively tailored the microstructure, resulting in a uniform dispersion of nano-Y₂O₃ particles and, after annealing, the precipitation of sub-micron (Ti,Zr)₅Si₃ silicides at α/β interfaces. The modified alloy exhibited significantly enhanced tensile strength, reaching 1348.2 MPa at room temperature in the as-built condition. After microstructural regulation via 900°C heat treatment, a basket-weave structure was obtained, leading to a balanced strength-ductility combination with a tensile strength of 1066.3 MPa and an elongation of 19.1%. The alloy also maintained superior tensile performance from 500°C to 700°C, and the creep life at 500°C was doubled compared to the unmodified counterpart, demonstrating exceptional creep resistance. The improvement is attributed to a synergistic mechanism combining solid-solution strengthening, effective dislocation pinning by thermally stable Y₂O₃ nanoparticles, and interface stabilization via silicides that collectively hinder dislocation glide and retard creep damage. This work provides a viable pathway for designing high-performance AM titanium alloys for critical high-temperature applications.