Small angle neutron scattering from Nd15Fe77B118and Nd15Fe76Al1B118permanent magnets

Domain walls, grain boundaries of sintered Nd
15
Fe
77
B
8
¹¹
and Nd
15
Fe
76
Al
1
B
8
¹¹
permanent magnets with different heat treatments have been examined by small-angle neutron scattering experiments. The results indicate that (1) there are many Bloch walls in the grains (Nd
2
Fe
14
B) which form a thin layer containing the c-axis of the tetragonal Nd
2
Fe
14
B, the thickness of which is ∼70A, and (2) there are film-like precipitates along the grain boundaries where thickness decreases from 60 A to 40 A by heat treatment at 600°C for 1 h after sintering, correlating with the coercive field increasing.