CAJ | 학술논문

The double hard magnetic phase magnets with nominal compositions of Nd30-xDyxFe69B1 (x=2, and 4) (wt.%) were pre-pared. The magnetic properties of the magnets were measured with a NIM-2000H hysteresigraph. The crystalline structures of the magnets were identified by X-ray diffraction (XRD). The Rietveld refinement was carried out using the FULLPROF software. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were carried out in order to investigate the microstructure of the magnets. It showed that the magnets consisted mainly of Nd2Fe14B phase, and some Nd-rich phase. Two types of matrix-phase grains in dark grey and light grey were found in the magnets with x=2 and 4. The Dy content was obviously dif-ferent in the two types of grains, which proved that the double hard magnetic phases (Dy-rich and Dy-lean phases) coexisted in the magnet. It revealed that the Nd-rich phases in junction regions had fcc structure, with the unit cell parameter of about 0.52-0.56 nm. The weak superlattice spots were found in the SAD patterns of the junction Nd-rich phases with large scale. The double hard mag-netic phase structure seemed to improve the magnetic properties of NdFeB magnets with high coercivity, while decrease the con-sumption of Dy element, compared with the single alloy magnet.