Recent Development of Soft Magnetic Materials

Three large topics for recent soft magnetic materials, such as ultra thin grain oriented silicon steels, nanocrystalline magnetic materials and 6.5wt% Si-Fe alloy sheets are reported. The ultra thin grain oriented silicon steels are known to have extremely low iron loss. Lately, it is reported the domain width of the ultra thin grain oriented silicon steels can be controlled by changing grain size. By this method very low iron loss can be realized without additional domain refining technique. The nanocrystaline magnetic materials are made by recrystallizing the amorphous materials. Since the effective magnetic anisotropy of the material is small, the nanocrystaline materials have fine soft magnetic properties. The 6.5wt% Si-Fe alloy has properties of small magnetostriction and poor ductility. Recently the sheets are commercially developed and used for high frequency transformers.