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

The high-temperature coercivity of mechanically alloyed and subsequently annealed RCo
₅
(R=Sm and Y) is studied. The annealed materials have the hexagonal CaCu
₅
structure with 2:17 (or 1:7) regions as a minor phase. High-temperature magnetic measurements show that the coercivities of materials decrease with increasing temperature from room-temperature to 873 K, but that the temperature coefficient of the coercivity of YCo
₅
is much smaller than that of SmCo
₆
. This behavior is explained in terms of the intrinsic temperature variation of the magnetocrystalline anisotropy.