Titanium alloy with synergistic enhancement of strength and toughness based on molybdenum equivalent design: Microstructure evolution and strengthening-toughening mechanism

• Mo equivalent design enables rapid and cost-effective composition optimization for ultra-high strength and toughness titanium alloys, replacing traditional trial-and-error methods. • Increasing Mo equivalent transforms β grains from columnar to equiaxed, refining grain size and reducing α phase content, with 6Mo alloy achieving optimal balance of strength (984 MPa), plasticity (12.8%), and toughness (74 MPa·m1/2). • The strengthening and toughening mechanisms are primarily solid-solution strengthening of Mo, β grain refinement, and α/β phase content modulation. • The study provides a theoretical foundation for developing new titanium alloys with synergistic strength and toughness for aerospace applications.