Manipulating the interfacial structures in titanium alloys containing interstitial solutes delivers ultra-high strength and ductility

H Zhang and XZ Li and JY Zhang and SZ Li and SH Gao and G Liu and J Sun, INTERNATIONAL JOURNAL OF PLASTICITY, 187, 104288 (2025).

DOI: 10.1016/j.ijplas.2025.104288

Design structural characteristics of interfaces is the key for ultra- strong titanium (Ti) alloys by tuning polymorphic alpha-precipitates. However, the conventional tri-modal structure, characterized by various interfaces, usually shows large ductility but low yield strength caused by numerous soft alpha-precipitates. This work focuses on manipulating multiple interfacial structures to endow a newly designed tri-modal Ti-4.9Al-4.4Cr-2.45Mo-1.6Zr alloys with the superior strength-ductility synergy assisted by interstitial solutes, beyond conventional high- strength Ti alloys. Here, an interstitial solute alloying strategy is utilized not only to form hard-yet-deformable alpha-precipitates, but also to achieve the controllably stepwise alpha-precipitation sequence to manipulate interfacial structures and thus slip transmission modes in Ti alloys. In particular, the coherent twin boundaries (CTBs) between secondary alpha-nanolamellae formed via dislocation-interstitial atom interactions can efficiently hinder dislocation motion but promote dislocation transmission in the soft transformed beta-matrix. This strategy provides new insights into designing high-performance interstitial solute-tolerant alloys for cost-effective and lightweight applications.

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