High-temperature magnetic properties of mechanically alloyed SmCo5 and YCo5 magnets

The high-temperature coercivity of mechanically alloyed and subsequently an nealed RCo5 (R = Sm and Y) is studied. The annealed materials have the hexa gonal CaCu5 structure with 2:17 (or 1:7) regions as a minor phase. High-tem perature magnetic measurements show that the coercivities of materials decr ease with increasing temperature from room-temperature to 873 K, but that t he temperature coefficient of the coercivity of YCo5 is much smaller than t hat of SMCo5. This behavior is explained in terms of the intrinsic temperat ure variation of the magnetocrystalline anisotropy.