What are the maximum recommended operating temperatures for different magnet materials?

The maximum temperature at which a magnet becomes effective depends greatly on the permeation coefficient or "Pc" of the material. The Pc is a function of the magnetic circuit in which the magnet operates. The higher the Pc (the more "closed" the circuit), the higher the temperature at which the magnet can operate without becoming severely demagnetized. Here are approximate maximum operating temperatures for the various classes of magnet materials. At temperatures near those listed below, special attention may be required to ensure that the magnet does not become demagnetized.

Material	Approximate max. of Operating temperatures
Material	°C	°F
NdFeB	140	284
SmCo	300	572
Alnico	540	1,004
Ceramic	300	572
Flexible	100	212