Microstructure and Magnetic Properties of Submicron-grained Nd-Fe-B Anisotropic Bulk Permanent Magnets Prepared from Compressed Aligned Fine Powder via Hydrogenation-Disproportionation-Desorption-Recombination

Abstract

We applied Hydrogenation-Disproportionation-Desorption-Recombination (HDDR) treatment on compacts of fine powder of Nd-Fe-B-based alloys to obtain porous, submicron-grained bulk permanent magnets. The crystallographic orientation of the Nd₂Fe₁₄B particles was maintained in the porous magnets, which could be further densified to the full density by hot pressing. Significant improvements over conventional HDDR-processed magnets were observed in the squareness of demagnetization curves for the full-density bulk magnets.