Magnetic fields have been widely used to control solidification processes. Here, high-speed synchrotron X-ray tomography was used to study the effect of magnetic fields on solidification. We investigated vertically upward directional solidification of an Al-Si-Cu based W319 alloy without and with a transverse magnetic field of 0.5 T while the sample was rotating. The results revealed the strong effect of a magnetic field on both the primary α-Al phase and secondary β-Al₅FeSi intermetallic compounds (IMCs). Without the magnetic field, coarse primary α-Al dendrites were observed with a large macro-segregation zone. When a magnetic field is imposed, much finer dendrites with smaller primary arm spacing were obtained, while macro-segregation was almost eliminated. Segregated solutes were pushed out of the fine dendrites and piled up slightly above the solid/liquid interface, leading to a gradient distribution of the secondary β-IMCs. This work demonstrates that rotating the sample under a transversal magnetic field is a simple yet effective method to homogenise the temperature and composition distributions, which can be used to control the primary phase and the distribution of iron-rich intermetallics during solidification.

磁场已广泛用于控制凝固过程。在这里，高速同步加速器 X 射线断层扫描用于研究磁场对凝固的影响。我们研究了在样品旋转时，在没有和有 0.5 T 横向磁场的情况下，Al-Si-Cu 基 W319 合金的垂直向上定向凝固。结果揭示了磁场对初生 α-Al 相和次生 β-Al _{5的强烈影响}FeSi 金属间化合物 (IMC)。在没有磁场的情况下，观察到具有大宏观偏析区的粗初生 α-Al 枝晶。当施加磁场时，获得了具有更小主臂间距的更细的枝晶，同时几乎消除了宏观偏析。分离的溶质被挤出细枝晶并堆积在固/液界面上方，导致二次 β-IMC 呈梯度分布。这项工作表明，在横向磁场下旋转样品是一种简单而有效的均匀化温度和成分分布的方法，可用于控制凝固过程中的初生相和富铁金属间化合物的分布。