The phenomena of melting and dendritic fragmentation are captured by using an in-situ device during the ultrasound-assisted solidification of a succinonitrile-acetone (SCN-ACE) alloy. The experimental results show that the dendrite arms detach from primary trunk due to the melting of the solid phase, which is caused by a moving ultrasound cavitation bubble. To quantify the interactions between the ultrasound cavitation bubble and the solidification front, a coupled lattice Boltzmann (LB) model is developed for describing the fields of temperature, flow, and solid fraction, and their interactions. The multi-relaxation-time (MRT) scheme is applied in the LB model to calculate the liquid-gas flow field, while the Bhatnagar–Gross–Krook (BGK) equation is executed to simulate the evolution of temperature. The kinetics of solidification and melting are calculated according to the lever rule based on the SCN-ACE phase diagram. After the validation of the LB model by an analytical model, the morphologies of the cavitation bubble and solidification front are simulated. It is revealed that the solidification interface melts due to the increase of the temperature nearby the cavitation bubble in ultrasonic field. The simulated morphologies of the cavitation bubble and solidification front are compared well with the experimental micrograph. Quantitative investigations are carried out for analyzing the melting rate of the solidification front under different conditions. The simulated data obtained from LB modeling and theoretical predictions reasonably accord with the experimental results, demonstrating that the larger the ultrasonic intensity, the faster the melting rate. The present study not only reveals the evolution of the solidification front shape caused by the cavitation bubbles, which is invisible in the ultrasound-assisted solidification process of practical alloys, but also reproduces the complex interactions among the temperature field, acoustic streaming, and multi-phase flows.

通过使用原位捕获熔化和树枝状碎片的现象琥珀腈-丙酮 (SCN-ACE) 合金超声辅助凝固过程中的装置。实验结果表明，由于固相的熔化，枝晶臂从主干上分离，这是由移动的超声空化气泡引起的。为了量化超声空化气泡与凝固前沿之间的相互作用，开发了耦合晶格玻尔兹曼 (LB) 模型来描述温度、流动和固体分数场及其相互作用。在 LB 模型中应用多弛豫时间 (MRT) 方案来计算液-气流场，同时执行 Bhatnagar-Gross-Krook (BGK) 方程来模拟温度的演变。凝固和熔化的动力学是根据基于 SCN-ACE 相图的杠杆规则计算的。在通过解析模型对 LB 模型进行验证后，对空泡和凝固前沿的形态进行了模拟。结果表明，凝固界面熔化是由于超声场中空化泡附近的温度升高所致。空化气泡和凝固前沿的模拟形态与实验显微照片进行了很好的比较。进行了定量研究以分析不同条件下凝固前沿的熔化速率。LB建模和理论预测得到的模拟数据与实验结果合理吻合，表明超声强度越大，熔化速度越快。