The quality of ultrasonically consolidated parts critically depends on the bond quality
between individual metal foils. This necessitates a detailed understanding of interface
microstructures and ultrasonic bonding mechanism. There is a lack of information on interface
microstructures in ultrasonically consolidated parts as well as a lack of consensus on the
mechanism of metal ultrasonic welding, especially on matters such as plastic deformation and
recrystallization. In the current work, interface microstructures of an ultrasonically consolidated
multi-material Al 3003-Ni 201 sample were analyzed in detail using optical microscopy,
scanning electron microscopy, energy dispersive spectroscopy, and orientation imaging
microscopy. Based on the results of microstructural studies, the mechanism of metal ultrasonic
welding has been discussed. The reasons for formation of defects/unbonded regions in
ultrasonically consolidated parts have also been identified and discussedMechanical Engineerin
