Achieve High Interfacial Bonding Strength of Ti/Al Laminated Composite at Room Temperature via Electropulsing-Assisted Ultrasonic Additive Manufacturing

Microstructure change of titanium layer in titanium/aluminium laminate metal composites during ultrasonic additive manufacturing

“…Since UC was first developed by White [6], it has become a widely utilised technique for manufacturing laminated metal structures. However, limited by the power of the present transducer, UC is relatively suitable for consolidation of metal/metal, where at least one has high plasticity, for instance Al/Al [7–9], Cu/Cu [10,11], Al/Cu [12,13], Al/Ti [14–16] and Al/steel [17,18]. In the case of harder/harder metals such as steel/steel [19–21], steel/Ti [22], steel/Ni [23], preheating, prolonging processing time and even post-treating are often required to obtain acceptable bond strength [19–21,23].…”

“…It is generally accepted that during the UC of soft metals, e.g., Al/Al or Al/Cu, interfacial bonding is primally produced by shear deformation-induced dynamic recrystallisation [7,13]. A recent theoretical calculation has revealed that the temperature increase caused by interfacial friction may surpass the recrystallisation threshold [25], and careful microscopy observations of the consolidated interface confirmed grain refinement, which is associated with dynamic recrystallisation [16,18,26]. Furthermore, dynamic recrystallisation can enhance atomic mobility and thus facilitate the formation of metallurgical bonds [27].…”