Flash heating-driven lamellarization of the primary α phase in a bimodal structured titanium alloy

Flash heating drives a non-equilibrium lamellarization of the primary α (α_p) into fine α_L clusters in bimodal TC17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr, wt.%) titanium alloy, forming hierarchical microstructures during sub-second heating across the β-transus (β_T) temperature. This provides a feasible route for advancing high-density interface architectures via ultrafast heating-induced phase transformations in titanium alloys. Key mechanisms are elucidated: (i) rapid peak heating (heating rates ≥100 °C/s) dissolves α_p into a transient β phase while preserving local elemental partitioning characteristics; (ii) diffusion of elements occurs without reaching equilibrium; (iii) decomposition of chemically heterogeneous regions into hierarchical multi-lamellar clusters upon quenching. And post-aging induces minimal morphological change in clusters while secondary α (α_s) lamellae precipitate in the β matrix.