Elevated-temperature (513K) ultrasonic welding of Al with Zn was investigated. The interface exhibits structures indicative of enhanced interdiffusion and local melting of Al–Zn solid solution. EDS analysis yielded an interdiffusivity value of 1.9μm2/s. The enhanced diffusion and melting could be attributed to high strain rate (about 103/s) plastic deformation in Al, which may increase the instantaneous vacancy concentration as high as about 0.10.

Enhanced Diffusion and Phase Transformations during Ultrasonic Welding of Zinc and Aluminum. I.E.Gunduz, T.Ando, E.Shattuck, P.Y.Wong, C.C.Doumanidis: Scripta Materialia, 2005, 52[9], 939-43