Potential of an Al-Ti-MgAl2O4 Master Alloy and Ultrasonic Cavitation in the Grain Refinement of a Cast Aluminum Alloy

Sreekumar, V.M.; Babu, N. Hari; Eskin, Dmitry

doi:10.1007/s11663-016-0824-5

Cited by 18 publications

(6 citation statements)

References 39 publications

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“…A 20 kHz ultrasonic vibration bearing an amplitude (peak-to-peak) of 60 µm was generated by a transducer (Sonicator 3000, Misonix Inc., Farmingdale, NY, USA) and applied to the melt for 15 min. Then, the melt was heated to 740 °C for pouring into low-carbon steel rectangular molds preheated at 350 °C to obtain master nanocomposite ingots weighing 500 g. A similar ultrasonic processing was used in prior research where more details are provided [14]. …”

Section: Methodsmentioning

confidence: 99%

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

Florián-Algarín

Marrero

et al. 2018

Materials

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This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl2O3 nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl2O3 nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl2O3 nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical conductivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding.

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Section: Methodsmentioning

confidence: 99%

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

Florián-Algarín

Marrero

et al. 2018

Materials

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“…In alloys containing potent particles (either peritectic systems or when external heterogeneous particles are added), UST can be employed either isothermally above the liquidus temperature or during cooling and terminating UST just above the liquidus temperature. In both these conditions grain refinement is improved by:De-agglomeration of particles by cavitation and simultaneous improvement in activation (wettability) of the particles by the penetration of parent liquid into the surface defects of the particles [2,47,50,73,74,75]; Excellent dispersion of the particles by acoustic streaming, as the melt in the liquid state has less resistance to fluid flow [6,47];narrow size distribution of nucleant particles throughout the melt and a reduced distance between adjacent potent nucleant particles [6,46,63];Reduced loss of inoculants by agglomeration and settling to the bottom of the casting [6]; Fragmentation of large, coarse primary intermetallic phases to fine structures that increase the rate of nucleation of primary grains [24,63,69,70]. …”

Section: Ust Applied To the Liquid Meltmentioning

confidence: 99%

“…De-agglomeration of particles by cavitation and simultaneous improvement in activation (wettability) of the particles by the penetration of parent liquid into the surface defects of the particles [2,47,50,73,74,75];…”

Section: Ust Applied To the Liquid Meltmentioning

confidence: 99%

Ultrasonic Processing for Structure Refinement: An Overview of Mechanisms and Application of the Interdependence Theory

et al. 2019

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Research on ultrasonic treatment (UST) of aluminium, magnesium and zinc undertaken by the authors and their collaborators was stimulated by renewed interest internationally in this technology and the establishment of the ExoMet program of which The University of Queensland (UQ) was a partner. The direction for our research was driven by a desire to understand the UST parameters that need to be controlled to achieve a fine equiaxed grain structure throughout a casting. Previous work highlighted that increasing the growth restriction factor Q can lead to significant refinement when UST is applied. We extended this approach to using the Interdependence model as a framework for identifying some of the factors (e.g., solute and temperature gradient) that could be optimised in order to achieve the best refinement from UST for a range of alloy compositions. This work confirmed established knowledge on the benefits of both liquid-only treatment and the additional refinement when UST is applied during the nucleation stage of solidification. The importance of acoustic streaming, treatment time and settling of grains were revealed as critical factors in achieving a fully equiaxed structure. The Interdependence model also explained the limit to refinement obtained when nanoparticle composites are treated. This overview presents the key results and mechanisms arising from our research and considers directions for future research.

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“…Recently an ultrasonic activation of spinel particles (potent substrates for aluminum) from an Al-1.3% Ti-1.8% MgAl 2 O 4 master alloy added to an aluminum casting alloy has been demonstrated as shown inFig. 5.15[108].…”

mentioning

confidence: 99%

“…Relation between grain size of A357 and the level of Al-Ti-MgAl2O4 master alloy addition with and without ultrasonic processing (adapted from[108]). Cavitation treatment may turn particles into active solidification sites by the following mechanism[50].…”

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confidence: 99%

High-Frequency Vibration and Ultrasonic Processing

Eskin

Tzanakis

2018

Solidification Processing of Metallic Alloys Under External Fields

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Chapter 5 High-frequency vibration and ultrasonic processing D.G. Eskin, I. Tzanakis 5.1 Historical overview of ultrasonic cavitation science and applications The application of ultrasound to the processing of liquids and slurries has a long history. The theory of oscillations was developed by Lord Rayleigh who laid the foundation for nonlinear acoustics. He also theoretically quantified the pressure pulse resulted from the imploding cavitation bubble and suggested that the acoustic pressure is directly related to the wave energy and velocity [1], which was experimentally confirmed by W.J. Altberg [2]. Significant contribution to the theory of cavitation was made by Ya.I. Frenkel [3] and E.N. Harvey [4] who explained why the cavitation threshold in liquids is well below the theoretical tensile strength of the liquid phase, suggesting a model of cavitation nuclei in real liquids as stable gas pockets at the surface imperfections of suspended particles. The pulsation of a cavitation bubble was described analytically by B.E. Nolting and E.A. Neppiras [5]. They introduced the resonance radius of the bubble. The bubble smaller that and around the resonance size will rapidly grow and then implode within one or two sound wave cycles. Each of the imploded bubble will generate large pressure pulse and create many even smaller bubbles, starting a chain reaction of bubble multiplication. The bubble larger than the resonance size will not implode but, being relatively stable, will pulsate around its size. The product of the number of cavitation bubbles in the unit volume and the maximum volume of a single bubble is called cavitation index. When this index approaches unity the amount of bubbles in the unit volume becomes so big that they substitute the liquid phase and the ultrasonic power transmitted to the liquid declines rapidly [6, 7]. This is the base of so-called shielding effect of the cavitation region, when the acoustic energy rapidly attenuates within the cavitation zone and does not propagate to the liquid volume. The practical aspects of ultrasonic cavitation started to attract the attention of physicists, chemists and other applied scientists and researchers. R. Wood and A. Loomis (1927) observed intensive acoustic streaming and fountaining, ultrasonic degassing, emulsification and atomization, cavitation damage of organic tissue, etc. [8]. The direct observation of cavitation became possible with the development of high-speed film cameras, high-brilliance impulse lamps and, eventually, laser illumination in the 1950s-1960s [9, 10, 11, 12, 13, 14]. The images taken with the exposure 0.5 to 5 msec enabled the in-situ study of the cavitation development, bubbles collapse and sonoluminescence. In recent years, in-situ studies of cavitation in liquid metals became possible using synchrotron radiation [15, 16, 17]. The application of vibrations to treating metals dates back to the 1870s when D.K. Chernov reported that shaking molten steel solidifying in a mold resulted in the formation of very fine crystals [18]. The ...

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Potential of an Al-Ti-MgAl2O4 Master Alloy and Ultrasonic Cavitation in the Grain Refinement of a Cast Aluminum Alloy

Cited by 18 publications

References 39 publications

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

Ultrasonic Processing for Structure Refinement: An Overview of Mechanisms and Application of the Interdependence Theory

High-Frequency Vibration and Ultrasonic Processing

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