Overcoming strength-ductility trade-off in titanium alloy by tailoring and regulating local-range ordered oxygen structure

YM Mao and QY Zhao and JH Geng and RQ Zhang and P Guo and N Wang and YN Chen and YQ Zhao, ACTA MATERIALIA, 298, 121430 (2025).

DOI: 10.1016/j.actamat.2025.121430

This study presents an unprecedented approach to overcoming the long- standing strength-ductility trade-off in Ti alloys. Nanoscale local- range ordered oxygen (LRO-O) structures were architecturally tailored within Ti-5553 alloys to enable concurrent dislocation engineering and stress dispersion. The strategy mitigates the detrimental effects of oxygen segregation and associated property degradation that previously limited high oxygen Ti alloys to laboratory-scale research. By regulating the size of LRO-O structures in alloys containing 0.36 wt % and 0.62 wt % oxygen-fabricated using powder metallurgy short-process technique-a groundbreaking combination of strength and ductility can be achieved across different yield strength levels (1300-1600 MPa). The Ti-5553-0.36O alloy demonstrates an optimal balance between strength, ductility and stress dispersion ability owing to its high strain hardening capability, attributed to a transition from planar slip to nonplanar cross-slip of dislocations, as well as the unique promotion of -type dislocation nucleation. The Ti-5553-0.62O alloy, despite showing improved performance compared to that of the conventional Ti-5553-0.12O alloy (which lacks LRO-O structure), is still inferior to the Ti-5553-0.36O alloy owing to the larger LRO-O structure of the Ti-5553-0.62O alloy. This research introduces a pioneering concept: tailoring the LRO-O structure can significantly enhance the performance of Ti alloys, offering a scalable and cost-effective alternative to expensive alloying elements and complex processing techniques.

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