Increased coercivity for Nd-Fe-B melt spun ribbons with 20 at.% Ce addition: The role of compositional fluctuation and Ce valence state

摘要

It is conventionally accepted that cerium can weaken the magnetic behavior of the Nd-Fe-B magnets. In the present work, however, it is found that the coercivity increases only with the addition of 20 at.% of cerium into the Nd-Fe-B alloy using physical performance measurement system compared to other samples with less or more Ce additions. Unique microstructure and phase composition for the 20 at.% Ce sample have been observed using scanning electron microscope and high resolution transmission electron microscope with energy dispersive spectra. Crystal structure for the alloys was characterized using X-ray diffraction and high resolution transmission electron microscope. Scattering lattice parameters due to compositional fluctuation and Ce valence state have been found to be the direct reason for the abnormal increase of the coercivity for the 20 at.% Ce alloy. (C) 2017 Elsevier B.V. All rights reserved.