Priyadarshi, Abhinav, Khavari, Mohammad, Bin Shahrani, Shazamin, Subroto, Tungky, Yusuf, Lukman, Conte, Marcello, Prentice, Paul, Pericleous, Kyriacos A ORCID: 0000-0002-7426-9999 , Eskin, Dmitry and Tzanakis, Iakovos (2021) In-situ observations and acoustic measurements upon fragmentation of free-floating intermetallics under ultrasonic cavitation in water. Ultrasonics Sonochemistry, 80:105820. pp. 1-14. ISSN 1350-4177 (Print), 1350-4177 (Online) (doi:https://doi.org/10.1016/j.ultsonch.2021.105820)

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Abstract

Grain refinement in alloys is a well-known effect of ultrasonic melt processing. Fragmentation of primary crystals by cavitation-induced action in liquid metals is considered as one of the main driving mechanisms for producing finer and equiaxed grain structures. However, in-situ observations of the fragmentation process are generally complex and difficult to follow in opaque liquid metals, especially for the free-floating crystals. In the present study, we develop a transparent test rig to observe in real time the fragmentation potential of free-floating primary Al3Zr particles under ultrasonic excitation in water (an established analogue medium to liquid aluminium for cavitation studies). An effective treatment domain was identified and fragmentation time determined using acoustic pressure field mapping. For the first time, real-time high-speed imaging captured the dynamic interaction of shock waves from the collapsing bubbles with floating intermetallic particles that led to their fragmentation. The breakage sequence as well as the cavitation erosion pattern were studied by means of post-treatment microscopic characterisation of the fragments. Fragment size distribution and crack patterns on
the fractured surface were then analysed and quantified. Application of ultrasound is shown to rapidly (<10 s) reduce intermetallic size (from 5 mm down to 10 μm), thereby increasing the number of potential nucleation sites for the grain refinement of aluminium alloys during melt treatment.

Item Type:	Article
Uncontrolled Keywords:	grain refinement; primary intermetallic crystal; fragmentation time; high-speed imaging; free-floating fragments
Subjects:	T Technology > TP Chemical technology
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Centre for Numerical Modelling & Process Analysis (CNMPA) Faculty of Engineering & Science > Centre for Numerical Modelling & Process Analysis (CNMPA) > Computational Science & Engineering Group (CSEG) Faculty of Engineering & Science > School of Computing & Mathematical Sciences (CMS)
Related URLs:	Publisher
Last Modified:	06 Jun 2022 14:48
URI:	http://gala.gre.ac.uk/id/eprint/34343

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