128 CHAPTER 12. PERMANENT MAGNETSA most favorable magnetic property of the Alnico alloys is that these materials have
very high Curie temperatures (700–850° C) which leads to excellent flux stability at elevated
temperatures. The Alnico alloys are chemically and metallurgically very stable. In fact,
Alnico is the only magnet material that has some long-term utility at temperatures up to
500°C. A drawback of the Alnico alloys is that their coercivity is low in comparison to
the rare-earth-based magnets described in Section 12.5. The non-linear behavior of the
B(H) curve in the second quadrant (Fig. 12.2) is a serious disadvantage in device design
and dynamic operation, and this limits the attainable energy product in spite of the high
remanence.
References
Buschow, K. H. J. (1988) in W. P. Wohlfarth and K. H. J. Buschow (Eds) Ferromagnetic materials, Vol. 4,
Amsterdam: North Holland Publ. Co. p. 1.
Buschow, K. H. J. (1998) in K. H. J. Buschow (Ed.) Handbook of magnetic materials, Amsterdam: North Holland
Publ. Co., Vol. 10, p. 436.
Givord, D., Lu, O., Rossignol, M. F. Tenaud, P., and Viadieu, T. (1990) J. Magn. Magn. Mater., 83, 183.
Guillot, M. (1994) in R.W. Cahn et al. (Eds) Materials science and technology, Weinheim: VCH, Vol. 3B, p. 1.