Glass-Forming Ability and Magnetization of (Fe, Co)-B-Si-(Nb, RE) (RE = Nd, Sm, Dy) Amorphous Alloys

The effect of the replacement of Nb by rare earth elements (RE = Nd, Sm or Dy) on glass-forming ability (GFA) and the magnetization of (Fe1−yCoy)79B17Si1Nb3−xREx (y = 0, 0.2, 0.4) alloys has been investigated. The RE-free melt-spun alloys do not show a glass transition and could not be obtained a single amorphous structure. On the contrary, the glass transition was confirmed in some Dy-contained alloys, and the alloys with the single amorphous phase have been obtained. In the alloys in which Nb is substituted with Sm, the alloys with a single amorphous phase were obtained. However, there is only one composition (y = 0 and 3 at% Sm) showing the glass transition. On the other hand, some Nd-contained alloys also exhibit the glass transition; however, the specimen with the single amorphous structure has not been obtained. These results indicate that the substitution of Dy is most effective to improve GFA. When Nb is substituted with Nd or Sm, the mass magnetization (σs) tends to increase. On the other hand, the substitution with Dy obviously reduces σs. These are due to the magnetic coupling properties between (Fe, Co) and RE elements.