Acoustic resonance for contactless ultrasonic cavitation in alloy melts

Tonry, Catherine; Djambazov, Georgi; Dybalska, Agnieszka; Griffiths, W.D.; Beckwith, Christopher; Bojarevics, Valdis; Pericleous, K.

doi:10.1016/j.ultsonch.2020.104959

Cited by 25 publications

(21 citation statements)

References 29 publications

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“…However, these methods also possess great disadvantages, such as the complicated production process requirements and high production costs. Recent studies show that the ultrasonic treatment in melt processing can improve the preparation and processing environment of materials, bringing about a better microstructure and improved properties [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] . Ultrasonic fields have acoustic cavitation and acoustic streaming effects [34] , [35] , [36] , which can reduce the interface energy between the particle and the melt, and thus activate the impurities to act as effective nucleation substrates.…”

Section: Introductionmentioning

confidence: 99%

Wetting of aluminium and carbon interface during preparation of Al-Ti-C grain refiner under ultrasonic field

Zhao

Ning

et al. 2021

Ultrasonics Sonochemistry

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Highlights Providing a new method for the preparation of Al-Ti-C grain refiner. The contact angle θ of aluminum-carbon interface is reduced under ultrasonic field. TiC particles are detached from the interface driven by sound pressure, which results that the wetting interface is updated in real time. The wetting and spreading of the aluminum melt on the graphite surface under ultrasonic field are simulated.

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Section: Introductionmentioning

confidence: 99%

Wetting of aluminium and carbon interface during preparation of Al-Ti-C grain refiner under ultrasonic field

Zhao

Ning

et al. 2021

Ultrasonics Sonochemistry

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“…This model, developed in COMSOL Multiphysics 5.2, has been validated for use in crucibles. 19 The model solves both the electromagnetic field and the acoustic response in the frequency domain. To solve the electromagnetic field, a 2D axisymmetric model is used for solving the full Maxwell equations with a current in the coil approximated by:…”

Section: Acoustic Resonance Modelmentioning

confidence: 99%

“…The electromagnetic field is solved in the coil, the melt, and the surrounding material (assumed to be air), with far field boundary conditions set to magnetic and electric insulation. The magnetic flux density obtained from this model is then used to calculate the magnetic pressure 19 :…”

Section: Acoustic Resonance Modelmentioning

confidence: 99%

“…The primary disadvantage of an immersed sonotrode is that limited volumes can be treated, and consequently multiple sonotrodes were required for large castings, as shown by Eskin and Eskin. 1 The use of an electromagnetic coil as a contactless source of ultrasound has been demonstrated to work in aluminum crucibles 19,20 containing up to 10.5 kg of metal. This process, using a high-frequency induction coil suspended close to the liquid-free surface 21 resulted in grain refinement and degassing after 2-4 min of treatment.…”

Section: Introductionmentioning

confidence: 99%

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Contactless Ultrasonic Treatment in Direct Chill Casting

Tonry

Bojarevics

Djambazov

et al. 2020

JOM

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Uniformity of composition and grain refinement are desirable traits in the direct chill (DC) casting of non-ferrous alloy ingots. Ultrasonic treatment is a proven method for achieving grain refinement, with uniformity of composition achieved by additional melt stirring. The immersed sonotrode technique has been employed for this purpose to treat alloys both within the launder prior to DC casting and directly in the sump. In both cases, mixing is weak, relying on buoyancy-driven flow or in the latter case on acoustic streaming. In this work, we consider an alternative electromagnetic technique used directly in the caster, inducing ultrasonic vibrations coupled to strong melt stirring. This ‘contactless sonotrode’ technique relies on a kilohertz-frequency induction coil lowered towards the melt, with the frequency tuned to reach acoustic resonance within the melt pool. The technique developed with a combination of numerical models and physical experiments has been successfully used in batch to refine the microstructure and to degas aluminum in a crucible. In this work, we extend the numerical model, coupling electromagnetics, fluid flow, gas cavitation, heat transfer, and solidification to examine the feasibility of use in the DC process. Simulations show that a consistent resonant mode is obtainable within a vigorously mixed melt pool, with high-pressure regions at the Blake threshold required for cavitation localized to the liquidus temperature. It is assumed that extreme conditions in the mushy zone due to cavitation would promote dendrite fragmentation and coupled with strong stirring, would lead to fine equiaxed grains.

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“…This method provides alloys with degassing, filtration and grain refinement [ 4 , 5 , 6 , 7 , 8 ]. Instead of the traditional immersed sonotrode, the contactless electromagnetic probe was recently developed to avoid melt contamination by probe damage due to corrosion in more reactive melts and to treat larger volumes of metal [ 9 , 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Mechanical Properties of Pure Aluminium through Contactless Melt Sonicating Treatment

et al. 2021

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A new contactless ultrasonic sonotrode method was previously designed to provide cavitation conditions inside liquid metal. The oscillation of entrapped gas bubbles followed by their final collapse causes extreme pressure changes leading to de-agglomeration and the dispersion of oxide films. The forced wetting of particle surfaces and degassing are other mechanisms that are considered to be involved. Previous publications showed a significant decrease in grain size using this technique. In this paper, the authors extend this research to strength measurements and demonstrate an improvement in cast quality. Degassing effects are also interpreted to illustrate the main mechanisms involved in alloy strengthening. The mean values and Weibull analysis are presented where appropriate to complete the data. The test results on cast Al demonstrated a maximum of 48% grain refinement, a 28% increase in elongation compared to 16% for untreated material and up to 17% increase in ultimate tensile strength (UTS). Under conditions promoting degassing, the hydrogen content was reduced by 0.1 cm3/100 g.

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Acoustic resonance for contactless ultrasonic cavitation in alloy melts

Cited by 25 publications

References 29 publications

Wetting of aluminium and carbon interface during preparation of Al-Ti-C grain refiner under ultrasonic field

Wetting of aluminium and carbon interface during preparation of Al-Ti-C grain refiner under ultrasonic field

Contactless Ultrasonic Treatment in Direct Chill Casting

Enhancement of Mechanical Properties of Pure Aluminium through Contactless Melt Sonicating Treatment

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