Abstract
The alignment of magnet powder such as Nd-Fe-B and Sr-ferrite under applied magnetic field was investigated. Initial magnetization curves of the unfixed powder showed sudden increase of magnetization at a field named Hrot which can be related to the beginning of rotation of the easy axis towards the applied field. Although the coercive force of Nd-Fe-B powder had changed by the substitution of Nd by Dy, the value of Hrot remained stable. When the volume proportion of powder capsulated in a sample holder had increased, the rotation was suppressed and the magnetization decreased. Nd-Fe-B powder formed many stable columns which are parallel to the applied field. The diameter of the columns are about few hundred microns. Inside the columns, magnet powder formed small chains aligned parallel to the applied field. Based on the model experiment where the powder particles are simulated by small magnets, the process of alignment was classified to three steps: technical magnetization; rotation/movement; alignment.
