High temperature soft magnetic materials: FeCo alloys and composites

We have systematically investigated the microstructural effects including grain size, precipitation, and structural order parameter on the high temperature magnetic and mechanical properties of FeCo-based commercial alloys. At high temperatures the equilibrium nonmagnetic precipitates significantly deteriorate the soft magnetic properties. Poor mechanical properties are mainly due to the nature of the ordered structure of FeCo alloys. Based on this understanding we have designed new magnetic composites by reinforcing FeCo alloys with high strength fibers. The magnetic and mechanical properties can thus be improved independently through optimizing the magnetic matrix and fiber network, respectively. These new magnetic composites show excellent soft magnetic and mechanical properties. In particularly, negligible creep has been observed at 600/spl deg/C.