Microstructure and mechanical properties evolution of near-β alloy Ti-4Al-6Cr-5Mo-5Nb-xTa

• Ta addition up to 2.0 wt.% fully dissolves in the near-β Ti-4Al-6Cr-5Mo-5Nb alloy, refining β grain size from 2.4 mm to 0.4 mm and increasing β phase fraction. • Optimal Ta content of 1.6 wt.% yields peak tensile strength of 735 MPa and fracture toughness of 55 MPa·m1/2, achieving a superior strength-toughness balance. • The study demonstrates a viable alloy design strategy to overcome the inherent strength-toughness trade-off in titanium alloys for aerospace fasteners. • Microstructural evolution, including α-phase coarsening and β-phase stabilization, underpins the enhanced mechanical performance.