Nd-Fe-B System Magnets with High Curie Temperature

Abstract

Magnetic Properties of Nd-Fe-B based magnets with Co-Al or Co-Ga addition were investigated. Co-Al or Co-Ga addition increases Curie temperature and coercive force, hence, improves temperature coefficient of magnetic induction, and makes it possible to use the Nd-Fe-B magnets at a higher temperature. The coercive force of the magnets with Co and Ga increases with increasing B content, while it hardly changes with B content for Co and Al containing magnets. Also, the magnets with Co and Ga have a high coercive force of about 12 kOe even at low boron content of 3.5 at % which is far lower than that of Nd₂Fe₁₄B. Itwas shown that intrinsic coercive force IHc for Nd-Fe-B system magnets with various composition changes with temperature with a relation of IHc^1/2∝T^2/3.