Superior high-frequency performances of Fe-based soft-magnetic nanocrystalline alloys

Soft-magnetic nanocrystalline alloys with ultralow power loss are strongly desired for high-frequency power electronic applications. In this work, an industrial ultrathin FINEMET alloy (Fe73.5Si15.5B7-Cu1Nb3) ribbon, with 14 mm in thickness, was fabricated by using a roller thermal conductivity-controlled cooling strategy coupled with a bottom blowing argon technique. A magnetic core made of the ultrathin ribbon exhibits excellent high-frequency soft-magnetic properties, with super high permeability of 48,000 at the condition of 1 A/m and 100 kHz and an ultralow core loss of 94 kW/m3 at the condition of 0.2 T and 100 kHz. It is found that the excess loss accounts for the largest proportion in power loss, and this proportion increases with decreasing thickness. The finest grain of nanocrystals, narrowest magnetic domain width, weakest transverse field-induced anisotropy, and considerably increased electrical re-sistivity (188 mU cm) synergistically contribute to the superior soft-magnetic performances at 100 kHz of the ultrathin alloy. This work demonstrates the attractive high-frequency application prospects of ul-trathin nanocrystalline alloys in power electronics and information communication due to their excellent performance and huge energy-saving effects, and provides new and comprehensive insights into the power loss of ultrathin nanocrystalline alloys.(c) 2023 Elsevier Ltd. All rights reserved.