TY - JOUR
T1 - Verification of the Mechanism of Grain Refinement by Ultrasonic Treatment of Aluminum-4 Wt Pct Silicon Molten Alloy
AU - Matsuda, Kazuki
AU - Takehara, Tsuyoshi
AU - Yang, Minghan
AU - Uno, Hikaru
AU - Kubo, Takashi
AU - Miyano, Gaku
AU - Yoshida, Makoto
N1 - Publisher Copyright:
© 2016, The Minerals, Metals & Materials Society and ASM International.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - 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.
AB - 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.
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U2 - 10.1007/s11661-016-3377-y
DO - 10.1007/s11661-016-3377-y
M3 - Article
AN - SCOPUS:84959482339
SN - 1073-5623
VL - 47
SP - 2509
EP - 2516
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
IS - 5
ER -