Ultrasonic Processing of Metal Melts
1.Power ultrasound in molten metals and alloys shows various beneficial effects such as structuring, degassing, and improved filtration.
2.Ultrasonic promotes the non-dendritic solidification in liquid and semi-solid metals.
3.Sonication has significant benefits on the microstructural refinement of dendritic grains and primary intermetallic particles.
4.Furthermore, power ultrasound can be used purposefully to reduce the metal porosity or to produce meso-porous structures.
5.Last but not least, power ultrasound improves the quality of castings.
Ultrasonic Solidification
The formation of non-dendritic structures during solidification of metal melts influences the material properties such as strength, ductility, toughness, and/or hardness.
Ultrasonically altered grain nucleation: Acoustic cavitation and its intense shear forces increase the nucleation sites and number of nuclei in the melt. Ultrasonic treatment of melts result in a heterogeneous nucleation and the fragmentation of dendrites, so that the final product shows a significantly higher grain refinement.
Ultrasonic cavitation causes the even wetting of non-metallic impurities in the melt. Those impurities turn into nucleation sites, which are the starting points of solidification. Because those nucleation points are ahead of the solidification front, the growth of dendritic structures does not occur.