ALUPRO-MPI ULTRASONICS INC.
Large volume ultrasonic treatment of molten metals. Why it now finally works.
ALUPRO-MPI Ultrasonics Inc.
The research of ultrasonic vibration for metallurgical applications can be dated back to 1878 when Chernov proposed the original idea of improving cast metal quality by elastic oscillations. The injection of ultrasonic energy into molten alloys brings about nonlinear effects such as cavitation, acoustic streaming, emulsification, and radiation pressure, which are used to refine micro-structures, reduce segregation, and improve secondary phase formation and distribution.
pressure and temperature fluctuations in the melt. These pressure and temperature fluctuations are likely to induce heterogeneous nucleation in the melt. They are also likely to promote dendrite fragmentation by enhancing solute diffusion through acoustic streaming. However, there is no convincing evidence in the literature as to which mechanism, i.e. heterogeneous nucleation or dendrite fragmentation, is more important for grain refinement under ultrasonic vibrations.
Ultrasonic treatment of aluminum alloys, in general, has been studied extensively. It has been shown that the introduction of high intensity ultrasonic vibration into the melt can eliminate columnar dendritic structure, refine the equiaxed grains, and under some conditions, produce globular nondendritic grains. Mechanisms for grain refinement under ultrasonic vibrations have been proposed. They are related to ultrasonically induced cavitations, which produce large instantaneous