Abstract：In this article, the effect of powder size refinement on microstructure and magnetic properties was investigated by optimizing jet-milling process. It was discovered that, when the average particle size (sauter mean diameter) decreased from 2.8μm to 2.3μm, the milling efficiency decreased to 40% of original level, the homogeneity of the particles distribution was improved gradually and the oxygen content of the sintered magnet was increased from ~1000ppm to 2700ppm. Microstructure observation result showed that, the Nd-rich distributed more homogeneously and dense in the magnet sintered with refined powder, and the corresponding grain size distributed in the range between 3-8μm. With the powder refinement process, the coercivity of the magnet increased by 175kA/m while maintaining the same nominal composition.
2019, Vol. 26 