High-field hysteresis loop of Nd-Fe-B magnet and related materials

Magnetization measurements were made on single crystals of (Nd
1-x
DY
x
)
2
Fe
14
B and sintered materials of (Nd
1-x
Dy
x
)
15
Fe
77
B
8
with x = 0.33, 0.47 and 0.60, in high magnetic fields up to 15 T and at temperatures 4.2 - 320 K. The magnetization of the single crystals is not saturated in difficult directions even at 15 T, and no hysteresis is observed in the easy direction except at 4.2 K. The sintered materials aligned by a magnetic field before sintering exhibit a remarkable hysteresis loop, the coercive field amounting to 11T at 4.2 K. The coercivity of the sintered materials is related to the anisotropy of the single crystals with corresponding values of x.