In situ high speed imaging study and modelling of the fatigue fragmentation of dendritic structures in ultrasonic fields

Wang, Shen; Kang, Jinwu; Guo, Zhipeng; Lee, Tung Lik; Zhang, X.; Wang, Qiao; Deng, Chenglong; Mi, Jiawei

doi:10.1016/j.actamat.2018.11.053

Cited by 69 publications

(30 citation statements)

References 32 publications

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“…After inserting the idle sonotrode into the melt the location at C and B is almost undisturbed while cooling curve A shows a significant drop in the temperature. Location A in Figure 4a represents the cavitation zone beneath the sonotrode where the observed temperature drop is 660 • C, which is only 5 • C above the liquidus temperature of the Al-2Cu alloy [52]. When the temperature drops below the liquidus the cavitation zone is referred to as undercooled zone, which is also confirmed by the simulation (Figure 3b,c).…”

Section: Simulation Of Acoustic Streamingsupporting

confidence: 63%

“…The alloys and pure metal ingots were cast from commercial purity Al (99.7%), high purity Zn (99.995%), commercial purity Mg (99.91%), copper (99.9%) and silicon (99.4%). Al alloys with varying concentration of Si [45], Cu [37,51,52] and Mg [49] were cast with and without UST. Master alloys of Al3Ti1B and Mg-25Zr were introduced into the melt to understand the effect of nucleant particles [6,46].…”

Section: Metals and Alloys Investigatedmentioning

confidence: 99%

“…Master alloys of Al3Ti1B and Mg-25Zr were introduced into the melt to understand the effect of nucleant particles [6,46]. Approximately 135 to 210 cc of pure metals and alloys were melted and solidified in a clay-graphite crucible in most of the experiments presented in [6,43,44,47,49,52]. The melt temperature was chosen to ensure there was enough superheat to overcome the chill effect induced by the unpreheated sonotrode.…”

Section: Metals and Alloys Investigatedmentioning

confidence: 99%

“…Without the addition of potent grain refiners, Wang et al [52] investigated the grain refinement achieved when UST was applied to an Al-2Cu alloy during solidification over different temperature ranges from above the liquidus to complete solidification. It was found that when UST is terminated above liquidus temperature, there is no refinement in the grain size.…”

Section: Pure Metals and Alloysmentioning

confidence: 99%

See 3 more Smart Citations

Ultrasonic Cavitation Treatment of Metallic Alloys

Eskin¹,

Tzanakis²

2020

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The current trend in solidification research is to develop a generic, energy-efficient, economical, sustainable, and pollution-free technology that can be applied to different alloy systems. Ultrasonic-cavitation melt treatment (UST) is a rather universal technology that can be applied to conventional and advanced metallic materials, regardless of their composition, while being environmentally friendly, cost effective, and ready to be implemented in conventional casting technologies such as direct-chill, continuous, or shape casting, as well as in emerging technologies of additive manufacturing and nanocomposite materials. The beneficial effects of UST-such as in assisted nucleation, activation of substrates (wetting), deagglomeration and fragmentation of solid phases, degassing of the melt, and grain refinement of the as-cast product-stem from the growth, collapse, and implosion of cavitation bubbles as aresult of alternate fluctuations in ultrasonic pressure. Although successfully demonstrated on the laboratory and pilot scale, UST has not yet found widespread industrial implementation. This is mostly due to the lack of in-depth understanding of the fundamental mechanisms behind the improved metal quality and structure refinement. Thus, fundamental research is needed to answer the following practical questions: What is the optimum melt flow rate that maximizes treatment efficiency whilst minimizing input power, cost, and plant complexity? What is the optimum operating frequency and acoustic power that accelerates the treatment effects? What is the optimum location of an ultrasonic power source in the melt transfer system in relation to the melt pool geometry? Answering these questions will pave the way for widespread industrial use of ultrasonic melt processing with the benefit of improving the properties of lightweight structural alloys, simultaneously alleviating the present use of polluting (Cl, F) for degassing or expensive (Zr, Ti, B, Ar) grain refinement additives.

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Section: Simulation Of Acoustic Streamingsupporting

confidence: 63%

Section: Metals and Alloys Investigatedmentioning

confidence: 99%

Section: Metals and Alloys Investigatedmentioning

confidence: 99%

Section: Pure Metals and Alloysmentioning

confidence: 99%

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Ultrasonic Cavitation Treatment of Metallic Alloys

Eskin¹,

Tzanakis²

2020

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“…In this paper, we presented three important cases obtained from systematic in situ and real-time studies carried out in the past 8 years or so. The experiments were conducted via close collaborations with scientists of the Advanced Photon Source (APS), USA, the Diamond Light Source (DLS), UK, Synchrotron SOLEIL, France, and Swiss Light Source (SLS), Switzerland; more and systematic results have been published in [6][7][8][9][10]. The experimental observations and interpretations were complemented by modelling and simulation using Helmholtz equation for calculating the propagation of acoustic pressure in liquid metal; and the Gilmore model for calculating the pressure and velocity at the oscillating ultrasonic bubble wall [6][7][8]10].…”

Section: Introductionmentioning

confidence: 99%

Understanding the Highly Dynamic Phenomena in Ultrasonic Melt Processing by Ultrafast Synchrotron X-ray Imaging

Eskin

Connolley

et al. 2019

Light Metals 2019

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In this paper, we present some highlighted findings from our recent research on real-time and in situ studies of the fundamentals of ultrasonic melt processing, including (1) ultrasonic bubble implosion, oscillation in liquid and semi-liquid (semi-solid) metals and their interactions with the growing solidifying phases; (2) enhanced acoustic metal flow and their impact on the liquid-solid metal interface. The real time experimental phenomena were interpreted with the aid of calculating the propagation of acoustic pressure in liquid metals using the Helmholtz equation and bubble wall pressure and velocity profile during bubble oscillation using the classical Gilmore model. The research provides unambiguous real-time evidence and robust theoretical interpretation in elucidating the dominant mechanisms of microstructure fragmentation and refinement in solidification under ultrasound.

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Ultrasound frequency-dependent microstructures of electrodeposited Ni nanocrystals for modifying mechanical properties

Zhou

et al. 2020

J Mater Sci

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In situ high speed imaging study and modelling of the fatigue fragmentation of dendritic structures in ultrasonic fields

Cited by 69 publications

References 32 publications

Ultrasonic Cavitation Treatment of Metallic Alloys

Ultrasonic Cavitation Treatment of Metallic Alloys

Understanding the Highly Dynamic Phenomena in Ultrasonic Melt Processing by Ultrafast Synchrotron X-ray Imaging

Ultrasound frequency-dependent microstructures of electrodeposited Ni nanocrystals for modifying mechanical properties

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