Soft Magnetic Properties of (Fe, Co)-RE-B Amorphous Alloys with a Large Supercooled Liquid Region

Fe-based amorphous alloys with high B concentrations in (Fe, Co)-RE-B system were found to exhibit a large supercooled liquid region (ΔTx) in a composition range 22.5–30 at%B, 0–30 at%Co and 2.5–6 at%RE . The ΔTx values exceeding 50 K were obtained for a series of Fe62Co9.5RE3.5B25 (RE=Pr, Nd, Sm, Gd, Tb, Dy, Er) amorphous alloys. The Fe62Co9.5RE3.5B25 amorphous alloys exhibit good soft magnetic properties of 1.35 to 1.43 T for saturation magnetization, 1.0 to 3.8 A/m for coercive force, and 8300 to 12500 for permeability at 1 kHz in the annealed state for 600 s at 773 K . The synthesis of the (Fe, Co)-RE-B amorphous alloys exhibiting a large supercooled liquid region and good soft magnetic properties with a high saturation magnetization is promising for future development as a new type of soft magnetic material.