Analysis of mechanism for effectively coercivity increment in (Nd, Ce)-Fe-B diffusion magnets

In this work, we explore how Ce in (Nd, Ce)-Fe-B magnet optimizes the microstructure of the base magnet, and enhances Grain Boundary Diffusion (GBD) of Dy. As Ce/total rare earth (TRE) content increases from 0 wt% to 16.95 wt%，the coercivity of the base magnets decreased by 24.93 %. However, lower-melting-point Ce element tended to distribute in the grain boundaries (GBs), and the thickness of the GBs layer increased from 2.46 nm to 5.54 nm. This provided more pathways for the subsequent GBD. Importantly, the diffusion depth of Dy element increased, and more core-shell structure formed as Ce increased. It led to a higher coercivity increment. Compared to GBD magnets without Ce, the coercivity increment of GBD magnets with Ce/TRE = 16.95 wt% increased by 39.54 %.