Nonuniform-to-uniform structural transitions induced by ultrasonic vibrations

= 5.7 GHz) significantly facilitates atomic diffusion (10-1000 times as fast as that in the case free of UVs) and formations and motions of dislocations, resulting in nonuniform-to-uniform structural transitions and increases in the thicknesses of the joined Mg/Al interfaces. These results provide a way to understand how the applied UV acts on dislocations and atomic diffusion during the UV-assisted welding processes of Mg-Al and other systems.