Characterization of interfacial microstructures in 3003 aluminum alloy blocks fabricated by ultrasonic additive manufacturing

Ultrasonic additive manufacturing (UAM) is a solid-state processing technique that uses ultrasonic vibrations to bond metal tapes into near net-shaped components. The benefits of UAM include the production of complex geometries and the incorporation of smart materials to produce functional composites and join dissimilar metals. The majority of the current research focuses on processing parameter optimization to eliminate macroscopic void formation at the interface. The present study utilizes ion-channeling contrast imaging from a focused ion beam, electron backscattered diffraction and transmission electron microscopy to examine microstructural changes induced during the UAM process. The results indicate that there is a bonding mechanism due to localized plastic deformation of asperities that undergo recrystallization and grain growth across the interface. Evidence for localized solidification microstructures, generated due to frictional sliding between the sonotrode horn and the tape material, is also presented.