Core loss of ultra-rapidly annealed Fe-rich nanocrystalline soft magnetic alloys

Abstract Ultra-rapidly annealed (heating rate >10 4  K/s, annealing time 100−x B x and Fe 87−y B 13 M y where x = 12, 13, 14 , y = 1, 2 and M = Cu, Ni (HiB-Nanoperm) have recently been demonstrated with a saturation magnetic polarization ( J s ) up to 1.92 T and a low coercivity ( H c ) of less than 8 A/m. In this study the AC core loss ( P cm ) is estimated for HiB-Nanoperm at 50, 400 and 1000 Hz and is compared with existing amorphous, nanocrystalline and conventionally crystalline (Fe-Si) materials. The P cm of HiB-Nanoperm at 1.5 T, 50 Hz is demonstrated to be 5–15% that of Fe-3 wt% Si. In specific, Fe 86 B 13 Cu 1 displays losses that are 30% that of Fe-6.5 wt% Si steel while also possessing a 5% larger J s . For maximum magnetic polarization ( J m ) values greater than 1.5 T this same composition also exhibits some of the lowest core losses seen from all Fe-based nanocrystalline alloys across the frequencies tested in this study. Core loss separation and an estimation of the anomaly factor ( η ) for selected HiB-Nanoperm alloys is also undertaken and compared with a Fe-based amorphous alloy. The η of HiB-Nanoperm is seen to be lower than that of Fe-based amorphous alloy and is also observed to be positively correlated with saturation magnetostriction. The low core loss of HiB-Nanoperm is attributed to a reduced anomalous loss which may be brought about by the moderate magnetostriction of this alloy.