Please use this identifier to cite or link to this item:
http://bura.brunel.ac.uk/handle/2438/14083
Title: | In-situ observation of fragmentation of primary crystals by ultrasonic cavitation in water |
Authors: | Wang, F Tzanakis, I Eskin, D Mi, J Connolley, T |
Keywords: | Aluminum alloy;Ultrasonic processing;Primary crystals;Fragmentation mechanism;Cavitation;In-situ high speed filming |
Issue Date: | 2017 |
Publisher: | Springer International Publishing |
Citation: | Light Metals, pp. 213 - 219,(2017) |
Abstract: | Ultrasonic melt processing is a promising technique for micro-structural refinement in castings. Several mechanisms have been pro-posed for the observed effects, including cavitation-induced nucleation, activation of substrates and fragmentation. Until now, however, real-time experimental observations which could clarify any of the above mecha-nisms are very limited. For the first time we directly observed the frag-mentation of primary crystals formed in aluminum alloys by ultrasonic cavitation. The primary crystals were extracted from real Al alloys and subjected to ultrasonic processing in water with in-situ high-speed film-ing. The recordings of fragmentation of the primary crystals allowed us to observe the different mechanisms of fragmentation, depending on the mechanical properties and morphology of the primary crystals. The col-lapse of cavitation bubbles in water is less violent than that in liquid alu-minum due to the lower cavitation threshold, viscosity and surface ten-sion. Therefore the fragmentation mechanisms for the primary crystals observed in water should also be present for the same primary crystals in the more violent cavitation situation in liquid aluminum. |
URI: | http://link.springer.com/chapter/10.1007%2F978-3-319-51541-0_29 http://bura.brunel.ac.uk/handle/2438/14083 |
DOI: | http://dx.doi.org/10.1007/978-3-319-54541-0_29 |
ISSN: | 2367-1181 |
Appears in Collections: | Dept of Mechanical and Aerospace Engineering Research Papers |
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