Verification of the Mechanism of Grain Refinement by Ultrasonic Treatment of Aluminum-4 Wt Pct Silicon Molten Alloy

Kazuki Matsuda, Tsuyoshi Takehara, Minghan Yang, Hikaru Uno, Takashi Kubo, Gaku Miyano, Makoto Yoshida

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    8 Citations (Scopus)

    Abstract

    Ultrasonic treatment (UST) of molten metals produces a fine grain microstructure. Several mechanisms of grain refining by UST have been suggested; however, experimental verification has not yet established the actual mechanism. In this study, UST was applied to Al-4 wt pct Si molten alloy (1) above the liquidus temperature, (2) during undercooling before recalescence, (3) during recalescence, and (4) after recalescence. After UST treatment, the average grain sizes of the solidified samples were measured, and the effects of UST were evaluated. In the case of (1), the temperatures of the crucible, ultrasonic horn, and the atmosphere of the molten alloy were also confirmed above the liquidus temperature, and a finer grain structure was obtained. This result reveals that UST promotes the nonequilibrium nucleation mechanism. UST during (2) and (3) also caused finer grain microstructures, whereas (4) did not. UST during undercooling hastened nucleation. However, the previously reported mechanism of the breaking dendrite was not activated by UST after recalescence.

    Original languageEnglish
    Pages (from-to)1-8
    Number of pages8
    JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
    DOIs
    Publication statusAccepted/In press - 2016 Mar 2

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    ASJC Scopus subject areas

    • Condensed Matter Physics
    • Metals and Alloys
    • Mechanics of Materials

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