Three dimensional (3D) ultrasounds with 20 kHz frequency and 14–22 μm amplitudes were applied to the solidification process of Mg_97.7Y_1.4Al_0.9 alloy. With the increase of ultrasonic dimension and amplitude, both the primary Al₂Y particles and the principal α-Mg phase were significantly refined in combination with an increased proportion of Al₂Y/α-Mg parallel growth interfaces, while the eutectic Al₂Y phase changed from long strip to fine granular shape. The dynamic solidification mechanism was further explained on the basis of in-situ acoustic spectrum measurements. It was found that once tiny primary Al₂Y and α-Mg nuclei formed, they immediately strengthened acoustic field by facilitating bubble formation at their solid/liquid interfaces, and the subsequent bubble oscillation and collapsing in turn promoted their further nucleation by improving wettability and increasing local undercooling. The ultrasonically solidified alloy showed superior mechanical performances as compared with static solidification structures. The maximum tensile strength and plasticity achieved 271 MPa and 12.8% which were 1.41 and 1.36 times higher than static values, and the high temperature creep properties were enhanced as well.

将频率为 20 kHz、振幅为 14-22 μm 的三维 (3D) 超声应用于 Mg _97.7 Y _1.4 Al _0.9合金的凝固过程。随着超声尺寸和振幅的增加，初生 Al _{2 Y 颗粒和主 α-Mg 相均显着细化，同时 Al 2} Y/α-Mg 平行生长界面比例增加，而共晶 Al ₂ Y相由长条状变为细粒状。在原位声谱测量的基础上进一步解释了动态凝固机制。发现曾经微小的初生Al ₂Y 和 α-Mg 核形成后，它们通过促进其固/液界面处的气泡形成立即增强了声场，随后的气泡振荡和破裂反过来又通过改善润湿性和增加局部过冷度促进了它们的进一步成核。与静态凝固结构相比，超声凝固合金表现出优异的机械性能。最大抗拉强度和塑性达到271 MPa和12.8%，分别是静态值的1.41和1.36倍，高温蠕变性能也得到了提高。