Magnetic properties of the anisotropic Fe-Al-C permanent magnet within the temperature range of 4.2 to 1100 K

The intrinsic magnetic material parameters of the Fe-Al-C magnet an determined in the temperature range, from 4.2 to 1100 K. It is shown that magnetization in this alloy is well described by the spin wave theory for temperatures 4.2 to 520 K. For temperatures between 520 and 720 K a narrow plateau in the magnetization plot is present. Similar temperature dependences of the coercive force H-c, the anisotropy field H-a, and the anisotropy constant K-1 are observed. The analysis of the temperature dependence of the coercive field leads to the conclusion that the pinning model is valid for the temperature range 4.2 to 520 K. The temperature dependences of the domain wall energy gamma, the domain wall width delta(B), and the critical diameter of single domain particles D-c are determined. Moreover, the distribution of grain orientations is determined and it is shown that the experimentally determined torque curve for the Fe-Al-C magnet is a superposition of the torque originating from the magnetocrystalline anisotropy of K-carbide and alpha-ferrite.