Determination of intrinsic magnetic material parameters of Nd2Fe14B from magnetic measurements of sintered Nd15Fe77B8 magnets

Abstract The magnetic anisotropy constants K 1 and K 2 of Nd 2 Fe 14 B have been determined in the temperature range between 4.2 and 575 K using aligned sintered Nd 15 Fe 77 B 8 magnets. Magnetization curves measured perpendicular to the aligning direction were analysed taking into account the volume fraction of the Nd 2 Fe 14 B phase and the angular distribution of grain axes. The grain alignment was determined by means of magnetic domain observation and X-ray analysis. It is shown that for sintered magnets an analysis under the assumption of the validity of the so-called Sucksmith-Thompson plot leads to significant errors especially of K 2 . As a further method for the determination of the anisotropy constant K 1 measurements of the magnetic initial susceptibility parallel to the alignment direction are proposed. The experimental results of both methods are compared with each other.