Abstract
The magnetic-property changes in sintered NdFeB magnets with different content of Dy and Nb after electrochemical hydrogen charging (EHC) were investigated. The phases of Dy2Fe14B, NbFeB, and Fe2Nb are confirmed by energy-dispersive spectrometry (EDS) and selected area electron diffraction. The electron back-scatter diffraction (EBSD) and electrochemical test show that the amount of Nd-rich grain boundary phases as hydrogen diffusion channels and the concentration of hydrogen near the surface of the magnets increase with the addition of Dy and Nb. Before and after EHC, the surface roughness and magnetic properties were measured using a laser scanning confocal microscopy, pulsed field magnetometer and flux meter. The results revealed that the surface roughness of magnets increases, owing to the absorption of hydrogen. During EHC, the remanence (Br) remains unchanged, whereas the magnitudes of the coercivity, magnetic moment (Mt), and maximum energy density ((BH)max) decrease by different degrees because of the presence of Dy and Nb compounds. Hydrogen decreases the stability of the magnet in demagnetization field by reducing the critical energy required for magnetic moment rotation, nucleation of reverse domains, and expansion of domain walls, and the presence of Dy and Nb compounds exacerbates the stability.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
