Soft Magnetic Materials and Applications

A great variety of soft magnetic material has been developed with the aim of enhancing the magnetization, increasing the permeability, controlling the hysteresis loop shape or raising the working frequency while in all cases decreasing the magnetic losses. Besides the physical considerations, material shaping and cost are important parameters. It is thus not surprising to see that despite natural selection, hundreds of materials of very different natures (metallic, ceramic, glass) and properties remain on the market. Choosing the right material for a specific application is often a tricky compromise and, too often, a question of industrial culture. This chapter aims at helping the user to make the best choice possible and gives some keys to improving device design. The first part is devoted to magnetic losses, giving the most-used models in the low-frequency non-linear regime and the high frequency linear regime. The following section describes the different families of materials: lowalloyed steels, iron-cobalt alloys, iron-nickel alloys, amorphous and nanocrystalline alloys and soft ferrites. In each section, the fabrication process is described and tables of typical properties of most common materials are given. Finally there is a table of applications and matching materials.