Development and application of Fe-based soft magnetic bulk metallic glassy inductors

Abstract The characteristics and application fields of core inductors made of Fe-based glassy alloy powders have been reviewed based on the data of Fe-based bulk metallic glasses developed for the last two decades. Fe-based glassy alloys in Fe-Cr-(B,Si,P,C) and Fe-Cr-Nb-(B,P) systems have been used as core inductors in various electronic-magnetic devices. The commercialization is attributed to a bulk glass-forming ability in conjunction with good soft magnetic properties, high mechanical strength, high corrosion resistance and high thermal stability during annealing at the high temperature near glass transition temperature ( T g ). Besides, the possibility whether or not the application can be made even for Fe-based amorphous alloys without glass transition as well as bulk glass-forming ability is also discussed on the basis of fundamental properties for recently developed Fe-Cr-Nb-(B,Si,P) and Fe-Mo-(B,Si,P) amorphous alloys. It is concluded that the success of mass production application to magnetic core inductors is attributed to the utilization of Fe-based glassy type alloys with high glass-forming ability, high degree of magnetic softness (low coercivity, high effective permeability and low core losses), high mechanical strength and high corrosion resistance.