改良HDDR処理による高B_r型Nd-Fe-Co-B系磁石粉末の作製 Production of Nd-Fe-Co-B Magnet Powders Having High B_r by Modified HDDR Process
It is well established that the hydrogenation-decomposition-desorption-recombination (HDDR) process can produce anisotropic Nd<SUB>2</SUB>Fe<SUB>14</SUB>B-based magnet powders having high coercivities. In this study, we investigated effects of the intermediate argon (IA) treatment, where alloys are annealed under argon atmosphere after hydrogenation in the HDDR process, on magnetic properties of Nd<SUB>12.6</SUB>Fe<SUB>bal.</SUB>Co<SUB>17.4</SUB>B<SUB>6.5</SUB>Zr<SUB>0.1</SUB>Ga<SUB>0.3</SUB> magnet powders. It was found that magnetic anisotropy of magnet powders is improved with IA treatment time. On the other hand, their coercivities are decreased by the IA treatment longer than 10min. The magnetic properties of the magnet powders with diameters of 100-212μm produced through the IA treatment for 10min are as follows: B<SUB>r</SUB>=1.38T, H<SUB>cJ</SUB>=1000kA/m and (BH)<SUB>max</SUB>=334kJ/m<SUP>3</SUP>. Transmission electron microscope observation revealed that change in microstructures such as rapid growth of α-(Fe, Co) matrix, disappearance of (Fe, Co)<SUB>2</SUB>B and formation of a new phase (TE phase) occur in hydrogenated alloys during the IA treatment.
粉体および粉末冶金 46(1), 51-56, 1999-01-15
Japan Society of Powder and Powder Metallurgy