Effect of Metalloid Elements on the Structures and Soft Magnetic Properties in Alloys

The compositional dependence of metalloid elements on the as-quenched and nanocrystalline structures and soft magnetic properties in the Fe_85.2Si_xB_14-x-yP_yCu_0.8 melt-spun ribbons was investigated. The formation of amorphous structure in the as-quenched state was confirmed in a wide compositional range of 0 ≤ x ≤ 2 and 0 ≤ y ≤ 6 at.%. A remarkably low coercivity (7-20 A/m) is exhibited by the annealed samples having very fine (<; 30 nm in size) α-Fe nanocrystalline structure. It is indicated that the optimum P content is usable to control the formation of very fine α-Fe nanograins. Meanwhile, a small addition of Si is effective to prevent the formation of secondary phases and to obtain high saturation magnetic flux density. The nanocrystalline Fe_85.2Si₁B₉P₄Cu_0.8 ribbon exhibits the most excellent soft magnetic properties and has lower core loss than the commercially used materials, suggesting the potential application as magnetic core materials in electrical devices.