Solid parts were produced by Very High Power Ultrasonic Additive Manufacturing (VHP-UAM)
at room temperature using 150 μm thick tapes of 6061 aluminum and 110 copper alloys.
Processing was done at 20 kHz frequency over a range of parameters (26 –36 μm vibration
amplitude, 5.6 – 6.7 kN normal force, and 30.5 - 35.5 mm/s travel speed). Softening of materials
(up to about 14% in 6061 Al and 23% in 110 Cu) was noted facilitating enhanced plastic flow
and a reduction in interfacial voids. Evolution of fine recrystallized grains (0.3-4 μm in 6061 Al
and 0.3-10 μm in 110 Cu) from an initial coarser grain structure (up to 8 μm in 6061 Al and 25
μm in Cu) was observed at the build interface regions. Bonding between layers in both materials
seems to have occurred by dynamic recrystallization and movement of grain boundaries across
the interface. The energy required for the above physical processes is derived from interfacial
adiabatic plastic deformation heating.Mechanical Engineerin
