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 (Tg). 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.