Microstructural Evolution and Competing Deformation Mechanisms in Aerospace Titanium Alloys: A Review

Aerospace load-bearing components require materials that exhibit high specific strength, excellent fatigue resistance, and superior environmental adaptability. Titanium alloys are indispensable for aerospace applications because of their exceptional mechanical properties, particularly their outstanding high specific strength, and their peak mechanical strength is typically achieved through solution heat treatment followed by artificial aging. This review systematically summarizes recent advances in the compositional design, microstructural evolution, and critical microstructure-property relationships of aerospace titanium alloys. It further highlights intrinsic effects of alloying elements on phase stability, dislocation behavior, and phase transformation pathways, and analyzes how lamellar, equiaxed, and bimodal microstructures regulate dislocation transfer, local strain partitioning, and damage evolution. The interactions and competition among deformation and phase-transformation mechanisms, including slip anisotropy, deformation twinning, stress-induced phase transformations, and ω-related processes, are critically assessed. However, unresolved challenges remain in quantitatively characterizing multi-mechanism coupling and local heterogeneity. To address these challenges, this review elucidates the transition rules of dominant mechanisms across different microstructures and proposes a high-precision digital composition-microstructure-property mapping framework to facilitate predictive and service-oriented alloy design.