Synchrotron X-ray Photography Study of Cavitation Bubble Distribution in an Al-Cu Melt

The spatial and size distribution of cavitation bubbles in Al-18wt.%Cu during ultrasonic melt processing at a fixed acoustic intensity input was exhaustively studied by utilizing synchrotron x-ray photography. The result reveals that the larger bubbles concentrate within an intense cavitation zone close to the radiation face of sonotrode, which is out-surrounded by a weak cavitation zone with bubbles sparse-inhabitation. Most cavitation bubbles obey a truncated size-Gaussian distribution, and the average size decreases as distanced away from the radiation face. The intensive cavitation zone contributes to an effectively refined solidification structure.