Permanent-magnet materials

M-type ferrites are mainly used as permanent magnet material. They have largely replaced the alnicos as preferred permanent magnet material, as a result of the lower material and processing costs. These ferrites were first introduced under the trade name Ferroxdure, the isotropic form in 1952 (22) and the anisotropic (crystal oriented) form in 1954 (23), and are widely available commercially under various trade names such as Oxid and Koerox. They cover about 55% of the world market of permanent magnet materials, corresponding to 1100 million U.S. doUars (1991), as weU as 55% of the U.S. market, at 300 million. 

Table 9. Magnetic Properties of Commercial Permanent Magnet Materials...

On his return home in 1911, Honda was appointed professor of physies at the new Tohoku Imperial University in Sendai, in the north of Japan this institution had been established only in 1906, when the finance minister twisted the arm of an industrialist who had made himself unpopular because of pollution eaused by his copper mines and extracted the necessary funds to build the new university. A provisional institute of physical and chemical research was initiated in 1916, divided into a part devoted to novel plastics and another to metals. This proved to be Honda s lifetime domain he assembled a lively team of young physicists and chemists. In the same year, Honda invented a high-cobalt steel also containing tungsten and chromium, which had by far the highest coercivity of any permanent-magnet material then known. He called it KS steel, for K. Sumitomo, one of his sponsors, and it made Honda famous. 

Disorder and Non-Collinear Magnetism in Permanent-Magnet Materials with ThMn12 Structure. 

Sintered samples of Sm2Fe17Xy with sufficient mechanical strength for use as the permanent magnetic materials are obtained by high-pressure... 

The operating state of a permanent magnet lies in the second quadrant of a B-H hysteresis loop since the magnet is always subject to its own demagnetizing field. Apart from its coercivity and remanence, a permanent magnet material is rated by its maximum energy product ... 

R. Coehoom, D. B. de Mooij, and C. de Waard, Meltspun Permanent Magnet Materials Containing Fe3B as the Main Phase , J. Magn. Magn. Mater. 80, 101 (1989). 

Buschow K.H.J. (1991) Novel permanent magnet materials, eh. 4, in Handbook, Supermagnets Hart magnetic materials, ed. G.J. Long, F. Grandjean, v. 331 of NATO Advanced Study Institute, ser. C, Kluwer Academic, 49-67. 

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