Hard magnetic properties of Nd-Co-B materials

A systematic investigation of the magnetic properties of neodymium-cobalt-boron alloys rapidly solidified by melt spinning is reported. Room-temperature coercivities and energy products as large as 10.2 kOe and 5.2 MGOe, respectively, have been observed in ribbons comprised primarily of tetragonal Nd2Co14B. We find that the characteristics of optimum as-quenched samples can be essentially recovered by annealing partially amorphous ribbons melt spun at higher quench rates. Although the Curie temperature of Nd2Co14B is Tc ≂995 K, the easy axis of magnetization changes from the c direction to the basal plane at Ts ≂560 K, and the practical magnetic properties deteriorate as Ts, rather than Tc, is approached.