Soft Magnetic Properties and Structures of Nanocrystalline Fe-Al-Si-Nb-B Alloy Ribbons

The soft magnetic properties and structures of nanocrystalline Fe-Al-Si-Nb-B alloy ribbons crystallized from an amorphous state were investigated. The best soft magnetic properties (effective permeability at 100 kHz of 23,000, core loss at 100 kHz, B
_m
=0.1 T of 9 W/kg, and saturation magnetostriction λ
_s
of +0.5×10
^-6
) were obtained for Fe
₆₆
Al
₈
Si
₁₄
Nb
₃
B
₉
alloy ribbons. These new alloy ribbons were composed of bcc Fe-based alloy with grain diameters less than 200 Å. It is suggested that the good soft magnetic properties are due to the nanocrystalline microstructure of the Fe-Si-Al alloy.