Effect of Grain Boundary Diffusion of Pr<sub>6</sub>O<sub>11</sub>/Cu/Al Mixture on Coercivity of Sintered NdFeB

The mixture of Pr₆O₁₁, Cu and Al was used as a diffused medium the magnetic material, treated with grain boundary diffusion. The microstructure and magnetic properties of the diffusion magnet were studied by SEM, XRD and magnetic property tester. The results show that the rich-rare earth phase becomes more inclined to distribute along the grain boundary diffusion, wetting the main phase grain boundaries, and causing more main phase grains to separate from each other. Under the condition of 600 ℃×3 h diffusion, the coercivity of the magnet is higher than that of the original and heat-treated magnets under the same conditions. When diffusion ratio (Pr₆O₁₁): Cu∶Al is 70∶15∶15, the coercivity of the magnet reaches the maximum, which is 1433.6 kA/m, which is 5.96% higher than that of the original magnet. The diffusion of Pr/Cu/Al at grain boundary can effectively improve the coercivity of the magnet.