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

Abstract

This paper investigates the microstructural characteristics of Ti layer in ultrasonic additive manufacturing of Ti/Al laminate composites by electron backscattered diffraction and transmission electron microscopy. Results show that a face-centred cubic (FCC) phase is formed in the Ti matrix around the Ti/Al bonding interface, and it keeps and orientation relationship with hexagonal close-packed (HCP) Ti matrix. The phase transition from HCP to FCC occurs in the region with high shear strain, which is associated with the movement of Frank or Shockley partial dislocations. The high-volume fraction of FCC-Ti under high ultrasonic amplitude can favour the improvement in the Ti/Al interfacial bonding strength via enhancing the plastic deformability of Ti foil.