Microstructural changes during the disproportionation of Nd13Fe80B7 alloys

Effects of the disproportionation time on the anisotropy and the microstructures of Nd13Fe80B7 alloys were examined. It was found that when the disproportionation time was 5 min, the degree of anisotropy (DOA) of HDDR Nd13Fe80B7 anisotropy bonded magnet was 0.58. Moreover, with the prolonging disproportionation time, the DOA decreased monotonically, and the corresponding disproportionation microstructures changed from the early lamella to the final sphere. Comparisons for the lamella disproportionation microstructure and the spherical disproportionation morphology showed that the two disproportionated products were different not only in the components but also in the relationships among the disproportionated products. In the lamella disproportionated products, there are no Fe2B phases, and there existed special crystallographic relationship between NdH2 and alpha-Fe. It was concluded that the characteristics of the lamella disproportionated mixture contributed to the formation of anisotropy. (C) 2003 Elsevier B.V. All rights reserved.Materials Science, MultidisciplinaryPhysics, Condensed MatterSCI(E)EI6ARTICLE1-2136-14127