Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound

Wang, Bing; Tan, Dongyue; Lee, Tung Lik; Khong, Jia Chuan; Wang, Feng; Eskin, Dmitry; Connolley, Thomas; Fezzaa, Kamel; Mi, Jiawei

Abstract

Ultrasound processing of metal alloys is an environmental friendly and promising green technology for liquid metal degassing and microstructural refinement. However many fundamental issues in this field are still not fully understood, because of the difficulties in direct observation of the dynamic behaviours caused by ultrasound inside liquid metal and semisolid metals during the solidification processes. In this paper, we report a systematic study using the ultrafast synchrotron X-ray imaging (up to 271,554 frame per second) technique available at the Advanced Photon Source, USA and Diamond Light Source, UK to investigate the dynamic interactions between the ultrasonic bubbles/acoustic flow and the solidifying phases in a Bi-8%Zn alloy. The experimental results were complimented by numerical modelling. The chaotic bubble implosion and dynamic bubble oscillations were revealed in-situ for the first time in liquid metal and semisolid metal. The fragmentation of the solidifying Zn phases and breaking up of the liquid-solid interface by ultrasonic bubbles and enhanced acoustic flow were clearly demonstrated and agreed very well with the theoretical calculations. The research provides unambiguous experimental evidence and robust theoretical interpretation in elucidating the dominant mechanisms of microstructure fragmentation and refinement in solidification under ultrasound.

Citation

Wang, B., Tan, D., Lee, T. L., Khong, J. C., Wang, F., Eskin, D., …Mi, J. (2018). Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound. Acta Materialia, 144, 505-515. https://doi.org/10.1016/j.actamat.2017.10.067

• Journal Article Type: Article
• Acceptance Date: Oct 29, 2017
• Online Publication Date: Nov 3, 2017
• Publication Date: Feb 1, 2018
• 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: 144
• Pages: 505-515
• DOI: https://doi.org/10.1016/j.actamat.2017.10.067
• Keywords: Electronic, Optical and Magnetic Materials; Polymers and Plastics; Metals and Alloys; Ceramics and Composites
• Public URL: https://hull-repository.worktribe.com/output/700378
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S135964541730931X
• Additional Information: This article is maintained by: Elsevier; Article Title: Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound; Journal Title: Acta Materialia; CrossRef DOI link to publisher maintained version: http://dx.doi.org/10.1016/j.actamat.2017.10.067; Content Type: article; Copyright: © 2017 Acta Materialia Inc. Published by Elsevier Ltd.