Ultrasonic-promoted rapid TLP bonding of fine-grained 7034 high strength aluminum alloys

High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400 °C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60 s and holding time of only 3 min at 400 °C, and the shear strength of joints could reach 223 MPa. The joint formation mechanism and effects of ultrasounds were discussed in details.