Influences of element segregation on the magnetic properties in nanocrystalline Nd-Ce-Fe-B alloys
Résumé
The RE-rich (Ce1−xNdx)16Fe78B6 (x = 0–1) nanocrystalline alloys were prepared by melt-spinning method. The transmission electron microscopy equipped with EDS was employed to investigate the microstructure and rare-earth element segregation. The average Nd/RE ratios in 2:14:1 grains are 22, 52, 67, 74, 78, and 81% for the x = 0.1, 0.4, 0.5, 0.6, 0.7, and 0.8 alloys, respectively, which are larger than the nominal ratios, indicating a Nd segregation in 2:14:1 phase. The Nd/RE ratio changing with x shows a two-stage of increment: the average increment in x = 0.1–0.5 alloys is much higher than that of x = 0.5–0.8 alloys. The corresponding change is also observed in the plotted intrinsic parameters of cell volume V, hyperfine field Bhf, and spin reorientation temperature TSR of the 2:14:1 phase changing with x curves. The high Ce-contained RE-rich Nd-Ce-Fe-B with strong element segregation shows high coercivities and high performance/price ratio. The present results thus contribute to understanding the fundamental mechanism of Ce-contained Nd-Ce-Fe-B permanent magnets and taking advantage of the element segregation.