Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound
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.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Univ. of Hull (United Kingdom); Brunel Univ. London (United Kingdom)
- Sponsoring Organization:
- USDOE Office of Science (SC); Engineering and Physical Sciences Research Council (EPSRC); Royal Society (United Kingdom)
- Grant/Contract Number:
- GUP 23649; GUP 26170; AC02-06CH11357; EP/L019965/1; EP/L019884/1; EP/L019825/1
- OSTI ID:
- 1437763
- Alternate ID(s):
- OSTI ID: 1437372
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Vol. 144 Journal Issue: C; ISSN 1359-6454
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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