Effect of high magnetic fields on the microstructure in directionally solidified Bi–Mn eutectic alloy

The eutectic Bi/MnBi alloy has been directionally solidified in the presence of an axial magnetic field to investigate the influence of high magnetic fields on the growth of eutectic Bi/MnBi. The morphology and magnetic properties of the specimens indicate that a high magnetic field promotes the formation of MnBi fiber and makes the directional solidification structure of the eutectic more regular. The MnBi inter-rod spacing and rod diameters gradually increase with the magnetic field intensity. Furthermore, the magnetic field enhances the faceted growth of MnBi phase and the magnetic coercivities of the alloy. This may be attributed to the magnetic anisotropy and the shift of the eutectic point by the magnetic field.