Surface effects of hysteresis loop shapes in high-coercive-force crystallized amorphous alloys

Crystallized amorphous ribbons sometimes show hysteresis loops indicating the presence of two magnetic phases on a large scale. Crystallized ribbons of both Co
66
B
30
Si
4
and Fe
70.5
B
15.5
Tb
7
La
7
showed this behavior. In each case the crystallized ribbon consisted of a core of one structure surrounded by a skin of another. Removal of this skin by etching improved the shape of the demagnetization curve of the Fe-B-Tb-La alloy considered as a permanent magnet material.