Design of multi-heterogeneous structure and synergistic enhancement of strength-plasticity in Ti-6Al-4V alloy

A multi-heterogeneous microstructure (MHM) composed of large equiaxed α (αeqL), small equiaxed α (αeqS), dispersed α and lamellar α was designed through hot-rolling and aging treatment on bimodal microstructure (BM) in TC4 titanium alloy. The formed αeqS grains with abundant orientations contribute to coordinated deformation to enhance the plasticity. The retained dislocations and precipitated dispersed α phase respectively contribute to dislocation strengthening and precipitation strengthening to improve the strength. Moreover, the multiple heterogeneous interfaces fabricated in the MHM could promote the formation of geometrically necessary dislocations (GNDs) and enhance the heterogeneous effect to synergistically improve the strength and plasticity.