In-situ observations and acoustic measurements upon fragmentation of free-floating intermetallics under ultrasonic cavitation in water

Priyadarshi, A., Khavari, M., Bin Shahrani, S., Subroto, T., Yusuf, L. A. , Conte, M., Prentice, P. , Pericleous, K., Eskin, D. and Tzanakis, I. (2021) In-situ observations and acoustic measurements upon fragmentation of free-floating intermetallics under ultrasonic cavitation in water. Ultrasonics Sonochemistry, 80, 105820. (doi: 10.1016/j.ultsonch.2021.105820)

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: Articles
• Additional Information: This work was financially supported by the UltraMelt2 project (grant EP/R011001/1, EP/R011095/1 and EP/R011044/1) funded by the UK Engineering and Physical Sciences Research Council (EPSRC).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Yusuf, Dr Lukman and Prentice, Dr Paul

Creator Roles

Yusuf, L. A.: Formal analysis, Investigation
Prentice, P.: Supervision, Writing – review and editing

• Authors: Priyadarshi, A., Khavari, M., Bin Shahrani, S., Subroto, T., Yusuf, L. A., Conte, M., Prentice, P., Pericleous, K., Eskin, D., and Tzanakis, I.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Ultrasonics Sonochemistry
• Publisher: Elsevier
• ISSN: 1350-4177
• ISSN (Online): 1873-2828
• Published Online: 02 November 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Ultrasonics Sonochemistry 80: 105820
• Publisher Policy: Reproduced under a Creative Commons License