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

Sintered Nd-Fe-B magnets are produced by axial die pressing or isostatic pressing and cut into octagonal prisms with their alignment direction within the octagonal plane. The alignment coefficients for two samples with different coercivity are determined. The magnets are first saturated in their alignment direction then demagnetized with a bit by bit increasing pulsed field applied at different inclination angles from the alignment direction. In between each demagnetization step, the remaining remanence in the initial direction is measured by means of a Helmholtz coil. Finally, the knee field strength which is defined by the field strength at which the magnets are demagnetized to 90% of the initial saturation value is deduced.