Glass-Forming Ability and Magnetic Properties of $({\rm Fe}_{0.80}{\rm Co}_{0.20})_{96\hbox{-}{x}}{\rm B}_{{x}}{\rm Si}_{{1}}{\rm Nb}_{{3\hbox{-}{y}}}{\rm Y}_{{{\rm y}}}~({{x}}={15}, 17)$ Amorphous Alloys

The glass-forming ability (GFA) and the magnetic properties of the (Fe
_0.80
Co
_0.20
)
_96-x
B
_x
Si
₁
Nb
_3-y
Y
_y
(x = 15, 17) amorphous alloys have been studied. It was confirmed that GFA is enhanced by replacing Nb with Y. Yttrium gives a complex effect on the magnetization. When Y content is increased, the saturation mass magnetization (σ
_s
) decreases first. However, the σ
_s
then increases and exhibits a maximum ~2 at% Y. The value of σ
_s
of the alloy with x = 17 and y = 2 in an as-quenched state is 211 × 10
_-6
Wb m/kg, which is slightly larger than that of the Y-free alloy with the same B content. The values of the coercivity of these alloys are less than 10 A/m in an as-quenched state. The coercivity shows a tendency to decrease with increasing Y content, which means the increase of GFA. These results indicate that the partial replacement of Nb by Y in the Fe-Co-B-Si-Nb alloys is useful to the simultaneous achievement of high GFA, high σ
_s
, and good soft magnetic properties.