The fluorine salt oxide molten-salt electrolytic Dy-Cu alloy was used as a grain boundary diffusion source
instead of the doped Dy-Cu alloy. The microstructure and coercivity of the GBDPed magnets with the different
diffusion times were studied. The results show that the coercivity increased with the increase in the GBDP time.
The ability of the electrolytic Dy-Cu alloy to improve the coercivity of Nd-Fe-B is more advantageous than that
of the doped Dy-Cu alloy. Microstructure analysis shows that the segregation and metal inclusion, a small
amount of Dy₂O₃, and the poor synergy diffusion between Dy and Cu lead to the unsatisfactory performance of
the doped Dy-Cu alloy to improve the coercivity. The diffusion rate and depth of the GBD source improved by
replacing the doped alloy with an electrolytic alloy.