Optimizing mechanical properties of near-α high-temperature titanium Alloys: Processing, microstructure and strengthening-toughening mechanisms

Near-α titanium alloys are widely applied in the aerospace sector; however, the demand for higher aircraft efficiency necessitates superior high-temperature resistance. Although alloying, compositing, and process control are established approaches for enhancing mechanical properties, their specific underlying mechanisms and key influencing factors remain not fully understood. This paper compares the preparation processes, microstructure evolution, and strengthening-toughening mechanisms of these optimization strategies. In terms of microstructure regulation, key factors include grain size, second-phase formation (reinforcements and precipitates), solute element content, and morphology. Notably, grain refinement and the regulation of Ti 3 Al/silicide precipitation behavior emerge as common mechanisms across all three methods. Mechanistically, tensile strengthening involves dislocation pinning, reduced mean free path, and back stress, while creep resistance stems from suppressing dislocation climb and interfacial diffusion. Plasticity is enhanced by mitigating strain localization and facilitating multi-slip activation. Comparative analysis reveals temperature-dependent trends: For 500–600 °C matrix alloys, compositing and process control dominate strengthening, whereas process control is most documented for 650–700 °C matrix alloys. Despite universal trade-offs, process control best balances mechanical performance. Future research should focus on synergistic modification to achieve an excellent strength-ductility balance. Additionally, more efforts are needed to investigate the high-temperature properties of additively manufactured near-α alloys, and to explore diversified approaches to achieve higher service temperatures based on existing 650–700 °C grade matrices.