Simulation of the particle misalignment of hard magnets after compaction

The simulation of powder compaction for Nd-Fe-B, Sm-Co, and barium ferrite shows the influence of different static field strengths and different mold filling on particle misalignment. The final magnetization differs up to 20% . The processing determines the pressure activated processes in which the p article overcomes a volume barrier, characterized by elastic energy fluctua tions. Isostatic compaction shows less pressure activated processes as comp ared to uniaxial mold pressing. However, an improved magnetization of about 10% owing to isostatic pressing was observed only for spherical particles. The pressure activated processes determine particle density defects such a s cracks and pores, misalignment of c axes at the punch side, at corners an d at particle density defects, and internal stress areas with cold plastic flow. (C) 1999 American Institute of Physics. [S0021-8979(99)44508-6].