中文摘要：

在一块超声的地以内的 Sn-38.1% Pb 最容易溶解的合金的动态团结在 35 kHz 的频率被调查。当样品高度 H 被减少， macrosegregation 上的超声的效果变得更突出，并且球形的最容易溶解的房间的体积部分相应地增加。当 H 在液体合金等于波长时，超声的介绍扩大分发区域主要(Sn ) 阶段，而是还原剂最容易溶解、主要的 Sn-Pb (Pb ) 的领域阶段。同时， dendritic-equiaxed 结构的转变发生在主要(Sn ) 阶段，和它的谷物尺寸显著地在超声的地以内被减少。一旦 H 减少到 /2 和 /4，超声的地支持水晶成核并且压制体积液体合金的进一步的 undercooling。理论分析显示成穴效果和激动人心的效果由于声学的流导致的本地高压力是在动态团结期间统治最容易溶解的生长机制的主要因素。

英文摘要：

The dynamic solidification of Sn-38.1% Pb eutectic alloy within an ultrasonic field is investigated at a frequency of 35 kHz. As the sample height H is reduced, the effect of ultrasound on macrosegregation becomes more prominent, and the volume fraction of spherical eutectic cells increases correspondingly. When H equals the wavelength 2 in liquid alloy, the introduction of ultrasound enlarges the distribution region of the primary （Sn） phase, but reduces the domains of the Sn-Pb eutectic and primary （Pb） phases. Meanwhile, a ＂dendritic-equiaxed＂ structural transition occurs in the primary （Sn） phase, and its grain size is significantly reduced within the ultrasonic field. Once H decreases to 2/2 and 2/4, the ultrasonic field promotes crystal nucleation and suppresses further undercooling of the bulk liquid alloy. Theoretical analyses indicate that the local high pressure induced by the cavitation effect and the stirring effect due to acoustic streaming are the main factors dominating the eutectic growth mechanism during dynamic solidification.