Nature.com Oct 21, 2024
The aerospace industry relies on Ti alloys owing to their strength-to-weight ratio and corrosion resistance. In metastable 946-Ti alloys slow cooling from the 946-transus leads to partial transformation into coarse 945 laths which is detrimental to the mechanical properties. A refinement and decrease of 945 laths has been previously achieved in 946-Ti alloys with B4C additions. In these materials the ductility of 946-Ti is preserved and the TiB and TiC particles promote strengthening. However the mechanism of the 946-Ti stabilization remains unclear. Using atom probe tomography we propose that Mo enrichment in the 945-phase limits its growth by reducing the influx of Al from the 946-phase. The complex chemical environment near eutectic TiB is enriched in Al and TiO promoting heterogeneous nucleation of fine 945-phase. Increased TiO concentration is observed with the introduction of B4C. A fundamental understanding of the 945-refinement mechanism in Ti-alloys is critical for aerospace applications demanding high performance and reliability.