Nanocrystalline Soft Magnetic Materials

Abstract

Nanocrystalline structures offer a new opportunity for tailoring soft magnetic materials. The most prominent example are devitrified glassy FeCuNbSiB alloys which reveal a homogeneous ultrafme grain structure of bcc-FeSi with grain sizes of typically 10–15nm and random texture. Owing to the small grain size the local magneto-crystalline anisotropy is randomly averaged out by exchange interaction so that there is only a small anisotropy net-effect on the magnetization process. Moreover the structural phases present lead to low or vanishing saturation magnetostriction. Both the suppressed magneto-crystalline anisotropy and the low magnetostriction provide the basis for the superior soft magnetic properties comparable to those of permalloys or near zero-magnetostrictive Co-base amorphous alloys but at a higher saturation induction.