Improvements in properties of NdFeB magnets obtained via magnetron sputtering and thermal diffusion

The grain boundary diffusion process (GBDP) of Dy and DyAl on sintered NdFeB magnets was conducted via magnetron-sputtering deposition of Dy and DyAl films to enhance coercivity (H-cj). The magnetic properties, microstructure and anti-corrosion properties of Dy-surface-alloying NdFeB magnets obtained via magnetron sputtering and thermal diffusion were evaluated. The H-cj of the Dy95Al5-NdFeB magnet increases by 32.68%, while the remanence declines slightly. Furthermore, X-ray diffraction and microstructural analysis confirm the formation of Dy-rich shells, the higher-magnetic-anisotropy field of hard (NdxDy1-x)(2)(FeAl)(14)B magnetic phases and an optimised grain boundary structure, contributing to the H-cj enhancement of the magnet. The elemental distribution and diffusion mechanism of the magnets are also discussed. Moreover, the corrosion resistance of the Dy95Al5-NdFeB magnet is substantially improved by enhancing the electrochemical stability and optimising the distribution and morphology of the intergranular phases. The findings of this study are of substantial importance in the development of low-heavy rare-earth sintered NdFeB magnets. (c) 2023 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.