Soft Magnetic Materials for Ac applications

Abstract

Soft magnetic materials for ac applications call to mind the familiar Fe, Fe–Si, and Fe–Ni alloys commonly used for the production of components. Due to the isotropic nature of PM soft magnetic parts, design factors such as stacking and sheet thickness are not appropriate for the reduction of total losses. The success of the application is dependent on the shape and size of the part and the material properties. The production of Fe–Si and Fe– Ni alloyed PM parts is today an industrial process in which the magnetic properties are tailored by well defined process parameters such as compaction pressure, sintering time, and sintering temperature. However, the PM process permits the use of alloying elements and systems beyond the sphere of traditional soft magnetic materials. A common example is Fe–P alloyed soft magnetic materials where an addition of 0·8%P results in an isotropic part which without either shape or size adjustment is equivalent to a pure Fe stack of sheet thickness 0·65 mm. The addition of P enhances not only the soft magnetic properties of pure Fe but also those of the Fe–Si alloys. The extension of the material range available to PM to include both Fe–Si– P and Fe–P–Sn increases the flexibility of choice of magnetic and electrical properties combinations, PM process capacity, and total production costs. The effect of various process parameters on the magnetic properties of both Fe–Si– P and Fe– P–Sn are shown, as are examples of the advantages of these materials compared with conventional alloys for the solution of specific process or cost problems. PM/0574