Fabrication of hypereutectic MnBi/Bi magnetic functional composites by solidification in a magnetic field

Three different kinds of solidification process of hypereutectic Bi-Mn alloys with a magnetic field applied have been investigated. There are alignment microstructure of MnBi precipitated phase in the alloys oriented with their crystallographic c-axis parallel to the direction of the field in all these cases. The remnant magnetism of the alloys crystallized in the field is found to be strongly anisotropic. When Bi-Mn alloys were solidified from a temperature in the mushy zone below 355°C with 1. 0T, rapid formation and uniformed distribution of textured ferromagnetic MnBi phase occurred in the alloys and the structure was proved to be stable without a magnetic field applied. Moreover, the remnant magnetism of the alloys solidified in this process was well and no heat treatment was required. Therefore, MnBi/Bi functional composites with excellent magnetic properties could be prepared directly with high efficiency by solidification in a magnetic field.