Enhanced strength and ductility in α-titanium alloys through in-situ alloying via additive manufacturing

Enhancing the strength of titanium alloys through aluminum addition is well-established but often results in significantly reduced ductility. Additive manufacturing (AM) presents a novel approach to fabricating titanium alloys, addressing the persistent challenge of balancing strength and ductility. This study compares the microstructural and mechanical properties of typical Ti-Al alloys produced using conventional casting and AM techniques. The results indicate that, compared to their as-cast counterparts, AM-fabricated Ti-6Al alloys exhibit a remarkable 90 % improvement in yield strength and nearly double the tensile ductility. The enhanced performance of AM alloys is attributed to their refined microstructures, increased dislocation densities, and ultra-high solid solubility, resulting from AM's rapid solidification rates and complex thermal histories. Detailed characterizations reveal that these microstructural features contribute to increased strain hardening and enhanced plastic deformation capacity. This research underscores the potential of AM to revolutionize material properties through microstructural control, providing valuable insights for future alloy design and manufacturing strategies. • Additive manufacturing boosts grain boundary and dislocation strengthening for superior α-titanium performance. • Rapid solidification in AM α-titanium suppresses short-range ordering, significantly improving ductility. • Distinct dislocation behavior in AM and as-cast α-titanium leads to contrasting fracture mechanisms.