Thermomagnetic behavior of a duplex ferromagnetic alloy, Fe75Si15B10

The chill-cast alloy Fe75Si15B10 consists of submicron Fe2B rods in a Fe3Si matrix. The magnetically ’’hard’’ Fe2B has a higher Curie temperature than the magnetically ’’soft’’ Fe3Si, which leads to unusual thermomagnetic behavior during cooling in low fields. When the thermoremanent magnetization (TRM) of the Fe2B produces a demagnetizing field greater than the applied field, the Fe3Si magnetizes opposite to the applied field, thereby reducing the net internal field. However, the magnetic heterogeneity of the sample prevents the net internal field from reaching zero. Significant magnetization changes are also noted in the temperature range where the magnetic anisotropy of Fe2B changes from easy-axis to easy-plane.