GRAIN TEXTURE, Nd CONTENT AND PROCESSING CONDITION EFFECTS ON MAGNETIC PROPERTIES OF NdFeB COMPOSITE MAGNETS

Abstract

The effects of grain texture, Nd content, processing conditions on magnetic properties and behavior of NdFeB nanocomposite magnet were investigated. The results demonstrate that mechanically activated disproportionation and desorption–recombination combined with plastic deformation process (M-HDDR & D) is an effective way to produce anisotropic NdFeB -type magnet. Magnetic anisotropy significantly enhances the magnetic properties of Nd 16 Fe 76 B 8 nanocomposite magnet, with the intrinsic coercivity (H ci ), magnetic induction (Br), and the energy product (BH) max achieving 0.88 T, 676.8 kA/m, and 135.2 kJ/m3, respectively. Decrease in Nd content improves the remanence but deteriorates the coercivity of NdFeB ternary composites. A low annealing temperature or short annealing time leads to an incomplete recombination, while a high temperature or long annealing time may result in grain overgrowth, and the optimum processing condition is found to be 780°C × 30 min. Pinning mechanism dominates in the magnetic hardening mechanism of Nd 16 Fe 76 B 8 composites prepared by both complete and incomplete recombination process, and particularly reversal nucleation process is also responsible for the latter case.