The highly dynamic behaviour of ultrasonic bubble implosion in liquid metal, the multiphase liquid metal flow containing bubbles and particles, and the interaction between ultrasonic waves and semisolid phases during solidification of metal were studied in situ using the complementary ultrafast and high speed synchrotron X-ray imaging facilities housed respectively at the
Considerable progress has been made in studying the mechanism and effectiveness of using ultrasound waves to manipulate the solidification microstructures of metallic alloys. However, uncertainties remain in both the underlying physics of how microstructures evolve under ultrasonic waves, and the best technological approach to control the final microstructures and properties. We used the ultrafast synchrotron X-ray phase contrast imaging facility housed at the Advanced Photon Source, Argonne National Laboratory, US to study in situ the highly transient and dynamic interactions between the liquid metal and ultrasonic waves/bubbles. The dynamics of ultrasonic bubbles in liquid metal and their interactions with the solidifying phases in a transparent alloy were captured in situ. The experiments were complemented by the simulations of the acoustic pressure field, the pulsing of the bubbles, and the associated forces acting onto the solidifying dendrites. The study provides more quantitative understanding on how ultrasonic waves/bubbles influence the growth of dendritic grains and promote the grain multiplication effect for grain refinement. have been widely used in industry, e.g., in ultrasonic cleaning, sonochemistry, and medical treatment. In the past few decades, extensive laboratory results have demonstrated that applying ultrasound waves into solidifying liquid alloys can lead to the refinement of alloy microstructures. [1][2][3] Although ultrasound-induced grain refinement has been shown effective in many metallic alloy systems, almost all previous research have interpreted the mechanism of grain refinement based on post-mortem microstructural characterization of the solidified alloys and empirical correlation, if any, between the measured grain size and the input ultrasonic power. [4,5] A very recent high-speed imaging study of ultrasonic treatment of a solidifying organic transparent alloy revealed that the shock wave emitted from imploding bubbles can fracture the growing dendrites, [6] increasing the grain multiplication effect that leads to the enhancement of grain refinement. However, in situ and real time studies of the fundamentals of how the highly dynamic ultrasonic waves and the ultrasonic bubbles interact with the liquid metal, the semisolid and solid phases nucleated during solidification have not been reported mainly due to the difficulties in studying the bubble dynamics in the opaque liquid metal. In this paper, we report a number of in situ imaging studies of the dynamic behavior of ultrasonic bubbles in a Sn-13 wt pct Bi and a Bi-8 wt pct Zn alloy using the ultrafast X-ray phase contrast imaging (PCI) facility housed at the Advanced Photon Source (APS), Argonne National Laboratory, US. The real-time imaging studies are complemented by a numerical simulation of the bubble dynamics using the classical Gilmore model. [7] The experiments were carried out at the beamline 32-ID-B of APS, and the detailed description of the experiment can be found in References 8, 9. The undulator gap was set to 14 ...
The data presented in this article are related to the paper entitled ‘Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound’ [Wang et al., Acta Mater. 144 (2018) 505-515]. This data article provides further supporting information and analytical methods, including the data from both experimental and numerical simulation, as well as the Matlab code for processing the X-ray images. Six videos constructed from the processed synchrotron X-ray images are also provided.
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