|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Aluminum Alloys, Processing and Characterization
||In-situ Observation of Fragmentation of Primary Crystals by Ultrasonic Cavitation in Water
||Feng Wang, Iakovos Tzanakis, , Jiawei Mi, Thomas Connolley
|On-Site Speaker (Planned)
Ultrasonic melt processing is a promising technique for microstructural refinement. Several mechanisms were proposed for the observed effects, including cavitation-induced nucleation, activation of substrates and fragmentation. Until now, however, real-time experimental observations are very limited to clarify any of the above mechanisms. We for the first time directly observed the fragmentation of primary crystals formed in aluminum alloys by ultrasonic cavitation. The intermetallics were extracted from real Al alloys and subjected to ultrasonic processing in water with in-situ high-speed filming. The results allowed us to observe the different mechanisms of fragmentation, depending on the properties and morphology of the intermetallics. The collapse of cavitation bubbles in water is less violent than in liquid aluminum due the lower cavitation threshold, viscosity and surface tension. Therefore the fragmentation mechanisms for the intermetallics in water should also be present for the same intermetallics in the more violent cavitation situation in liquid aluminum.
||Planned: Light Metals