Mn-Bi系磁性材料に関する研究

概要

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An experimental study was made on the magnetic behavior of 40〜70 at % Mn-Bi system alloys with the samples prepared with (1) powder metallargy, (2) heat treatment in magnetic field, (3) cold rolling, (4) swaging method. The result are summarised as follows: (1) The magnetic properties are improved with sintering : especially, the effect of sintering on magnetic properties of anisotropic samples are very distinct in 4πI_<10k>, 4πI_r, 4πI_r/4πI_<10k> and (BH)_<max>. It is confirmed that fine particles of the compound grow in the applied field direction during pressing. (2) In the samples heat-treated in magnetic field, the ferro magnetic crystallite preferentially grow with their magnetically preferred orientation in the applied field direction. The orientation effect is enhanced with decreasing Mn content.(3) The oriented Mn-Bi compound is crushed in to fine particles by the cold rolling process. Consequently, the coercive force of this compound increases. And, the succeeding magnetic annealing improves the magnetic properties for these particles are re-aligned to the applied field direction. (4) It is found that in swaging method, the magnetic properties of specimens which are swaged in cast state and then heat treated in magnetic field, are improved with reduction of area. The value of maximan magnetic energy product is 6.1 MG・Oe in 40 at % Mn-Bi alloy with 92% reduction.
明治大学の論文