Nucleation Enhancement of Al Alloys by High Intensity Ultrasound

概要

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The utilization of ultrasound is expected to be applied to many casting process because of the high efficiency of ultrasound energy. The present study attempts to evaluate the effect of ultrasound energy on microstructure of castings, and high intensity ultrasound was injected into A356 and A390 alloy melt for refinement of primary phase without adding a chemical refiner. The microstructure refinement, especially primary alpha phase, could not be achieved in A356 alloy with simply ultrasound injection into alloy melt, although ultrasound was injected for 20 min. However, the influence of ultrasound on the microstructure in A390 alloy is very clear. Primary silicon of A390 alloy with ultrasound injection into melt was very small and dispersed uniformly in alloy matrix. In addition, the primary Si size was decreased with an increase the ultrasound injection time from 82 to 8 μm. As compared with A356 alloy, however, A390 alloy shows the nucleation enhancement by ultrasound vibration of melt only. The reason that there is a difference of the refinement of primary phase between A356 and A390 alloy could be explained by solute cluster theory.
2009-07-25