Short-time annealing achieves interfacial equilibration and strength-ductility synergy in ultrasonic additive manufactured Ti/Al laminated composites

Ultrasonic additive manufacturing (UAM) was employed to fabricate Ti/Al laminated composites and elucidate the relationship between interfacial microstructure and macroscopic tensile behavior. The UAM process produced thermally asymmetric interfaces, where the Ti/Al interface experienced higher local temperatures and more intense plastic deformation, promoting partial dynamic recrystallization and Al grain refinement. In contrast, the Al/Ti interface underwent limited recovery and retained a softer structure. Digital image correlation (DIC) mapping revealed pronounced strain partitioning, with shear localization concentrated near the recrystallized Ti/Al interface. Subsequent short-time annealing induced grain coarsening, dislocation recovery, and stress relaxation at both interfaces, reducing hardness mismatch and improving strain compatibility. The heat-treated laminates exhibited smoother strain fields, more uniform deformation, and a simultaneous enhancement in strength and ductility. Correlative EBSD, TEM, and DIC analyses established a clear mechanistic link between interfacial microstructural evolution and macroscopic deformation response. The findings demonstrate that achieving an optimal strength-ductility synergy in UAM Ti/Al laminates relies primarily on regulating interfacial recrystallization and residual stress rather than merely strengthening the metallurgical bond.