Angular dependence of the demagnetization stability of sintered Nd-Fe-B magnets

The demagnetization behavior of commercial sintered Nd-Fe-B magnets was investigated for field directions inclined by 0°, 45°, and 90° with respect to the easy axis. For demagnetizing field strengths well below the coercivity, the reversible permeability parallel to the easy axis amounts to 1.03-1.05 and perpendicular to the easy axis to 1.12-1.17, depending on the alignment coefficient and the coercivity. For demagnetizing fields applied at an inclination angle of up to 45°, irreversible losses start at 90%-95% of the respective coercivity, independent on the alignment coefficient. For an inclination of 90°, irreversible losses arise at demagnetizing field strengths of about 130%-170% of the respective coercivity. Here, the demagnetizing stability increases with increasing alignment coefficient.