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A synchrotron X-radiography study of the fragmentation and refinement of primary intermetallic particles in an Al-35 Cu alloy induced by ultrasonic melt processing

Wang, Feng; Eskin, Dmitry; Mi, Jiawei; Wang, Chuangnan; Koe, Billy; King, Andrew; Reinhard, Christina; Connolley, Thomas

Authors

Feng Wang

Dmitry Eskin

Chuangnan Wang

Billy Koe

Dr Andrew King A.King@hull.ac.uk
Reader in Music and Technology/ Head of School

Christina Reinhard

Thomas Connolley



Abstract

Using synchrotron X-ray high speed radiography, the fragmentation and refinement of pre-existing primary Al2Cu intermetallic dendrites induced by ultrasonic melt processing in a hypereutectic Al-35% Cu alloy were studied in-situ and in real time. The alloy was melted, contained and processed in a quartz tube crucible with a middle section of approximately 300 μm-thick channel where the observations were made. Direct observation of intermetallic fragmentation and detachment unambiguously confirms that the acoustic cavitation and streaming flow play a crucial role in fragmentation of the intermetallic dendrites. Furthermore, the remelting effect due to transport of hot liquid via acoustic streaming flow and the stress against the intermetallic dendrites caused by acoustic streaming flow are found to be the dominant fragmentation mechanism in the present experiments. It is also suggested that cavitation bubbles or bubble clouds contribute to fragmentation not only by mechanically fracturing the dendrites but also by facilitating the effect of acoustic streaming flow on dendrites. At last, clear observation of equiaxed intermetallic dendrites growing from small fragments after ultrasonic melt processing provides the first conclusive evidence of the refinement mechanism, i.e. the acoustic cavitation and acoustic streaming flow progressively break the intermetallic dendrites into small fragments. Most of these small fragments are able to survive and then act as nuclei for the subsequent solidification of intermetallic phases, consequently leading to intermetallic refinement in the solidified microstructure.

Citation

Wang, F., Eskin, D., Mi, J., Wang, C., Koe, B., King, A., …Connolley, T. (2017). A synchrotron X-radiography study of the fragmentation and refinement of primary intermetallic particles in an Al-35 Cu alloy induced by ultrasonic melt processing. Acta Materialia, 141, 142-153. https://doi.org/10.1016/j.actamat.2017.09.010

Journal Article Type Article
Acceptance Date Sep 7, 2017
Online Publication Date Sep 9, 2017
Publication Date 2017-12
Deposit Date Mar 2, 2018
Publicly Available Date Mar 5, 2018
Journal Acta Materialia
Print ISSN 1359-6454
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 141
Pages 142-153
DOI https://doi.org/10.1016/j.actamat.2017.09.010
Keywords Electronic; Optical and magnetic materials; Polymers and plastics; Metals and alloys; Ceramics and composites
Public URL https://hull-repository.worktribe.com/output/700529
Publisher URL https://www.sciencedirect.com/science/article/pii/S1359645417307450
Copyright Statement © 2017 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY
license (http://creativecommons.org/licenses/by/4.0/).

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