Verification of the Mechanism of Grain Refinement by Ultrasonic Treatment of Aluminum-4 Wt Pct Silicon Molten Alloy
Verification of the Mechanism of Grain Refinement by Ultrasonic Treatment of Aluminum-4 Wt Pct Silicon Molten Alloy
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DOI：
10.1007/s11661-016-3377-y
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
K. Matsuda;Tsuyoshi Takehara;Ming-sheng Yang;Hikaru Uno;T. Kubo;Gaku Miyano;M. Yoshida
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文献类型：
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作者：
K. Matsuda;Tsuyoshi Takehara;Ming-sheng Yang;Hikaru Uno;T. Kubo;Gaku Miyano;M. Yoshida
熔融金属的超声处理（UST）产生细晶粒显微组织。已经提出了几种通过UST细化晶粒的机制;然而，实验验证尚未建立实际的机制。在这项研究中，UST被应用于Al-4wt%Si熔融合金（1）高于液相线温度，（2）在过冷之前的再结晶，（3）在再结晶期间，和（4）在再结晶之后。在超声处理后，测量凝固样品的平均晶粒尺寸，并评估超声处理的效果。在（1）的情况下，坩埚、超声波焊头和熔融合金的气氛的温度也被确认为高于液相线温度，并且获得了更细的晶粒组织。这一结果表明，UST促进非平衡形核机制。在（2）和（3）中的UST也导致更细的晶粒显微组织，而（4）没有。过冷时的超声波加速形核。然而，以前报道的断裂枝晶的机制并没有被UST激活后，发光。
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.