Trifunctional local-range order oxygen structure enhanced strength-ductility and fatigue resistance in large-scale metastable titanium alloy

Research on high-performance Ti alloys incorporating oxygen (O) has remained a laboratory procedure and is hindered by the unresolved issue of O segregation-driven failure. Here, we demonstrate that O can tailor a nanoscale local range order O (LRO-O) structure between the oxide and random interstitials in Ti alloy. We introduce 0.36 wt% O into metastable Ti-5Al-5Mo-5V-3Cr alloy using a short-term powder metallurgy approach to produces large-scale materials. The LRO-O structure in designed alloy prevents crack initiation by promoting the active nucleation of -type dislocations and altering the slip modes during tensile and fatigue failure. The alloy has high strength (1.7 GPa), elongation (7.9%), and fatigue strength (1058.3 MPa), which outperforms many high-strength, high-O Ti alloys. Our findings provide a scalable, practical route to superior mechanical properties for Ti alloys without costly alloying elements. The authors demonstrate how interstitial oxygen can be used to tailor nanoscale structures in a Ti alloy, using a powder metallurgy technique, to prevent crack initiation and enhance strength.