Investigation on the solidification of Bi-Mn alloys under a high magnetic field

Solidification experiments of Bi­3-6wt%Mn alloys under a high magnetic field up to 10 T have been carried out. It is found that the primary BiMn grains in the Bi­Mn alloy rotate and align along the direction of the magnetic field. There are 3 kinds of structures of the BiMn phase according to the starting solidification zone. In the zone below the Curie point rod­like BiMn grains appear, in the zone above the Curie point and below the liquidus flake­like BiMn grains appear, and in the case above the liquidus temperature tightly piled flake­like BiMn grains are produced. In all these cases, the grains are aligned and orientated at <001> along the direction of the field. When the alloy with aligned rod­ like BiMn grains is reheated to below the Curie point, the alignment of BiMn is kept; and when reheated to above the Curie point, the alignment breaks down. It is shown that due to the magnetization force in the BiMn crystals by a high magnetic field, tips of the leaf­like crystals are broken. Figs 9, Refs 7.