異方性 MK 磁石の研究 (II) : 熱処理と組織について

概要

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The magnetic properties in the anisotoropic MK magnet alloy has been proved to be sensitive to the heat treatment. Effects of solution treatment, cooling conditions in magnetic field, and aging treatment on the magnetic properties were examined on the specimens of representative composition, and the optimum heat treatment was determined as follows : The specimens are solution-treated by heatng for 10 or 20 minutes at 1200 or 1250℃, and cooled in a magnetic field of 1500 oersteds or so. The optimum cooling rate for magnetic treatment is 1℃/sec when going from 900 to 800℃ The action of the field is effective from the Curie point to 150℃ below. In age hardening, the alloy is held for 1 or 3 hours at 600 or 625℃. The magnetic properties can be improved by the growth of columnar crystals. On the specimens subjected to the optimum heat-treatment, any precipitation cannot be discerned. It is suggestive that the magnetic anisotropy and high coercive force of this alloy associated with the subdivision of materials by needle-like pseudoprecipitations, directed by the magnetic cooling in the field and developed during aging.
社団法人日本鉄鋼協会の論文
1956-12-01