Effect of Nd70Al30 Grain Boundary Modified on Heavy Rare Earth Diffusion in Sintered NdFeB
(PrNd)30Fe69-xB1Mx+y Nd70Al30(y=00.25％、0.50％、0.75％、1.00％)diffusion precursors were prepared by the grain boundary modified method.The effect of the grain boundary modified alloy Nd70Al30 content on the coercivity by grain boundary diffusion was studied by BH tracer(NIM20000),EPMA,and Transmission Electron Microscope(TEM).The results showed that with the addition of Nd70Al30,the coercivity of the magnet increased significantly,whether it diffused par-allel or perpendicular to the C axis.When the addition of the Nd70Al30 alloy is 1.00％,the coercivity of the magnets reaches about 1800 kA/m,and the anisotropy of coercivity is significantly improved.The microstructure results showed that the grain boundary modification effectively reduced the enrichment of Tb element when diffusing applied perpendicular to the c-axis,and formed a continuous Tb-rich shell structure in the magnet deeply.The Fe element in grain boundary phase and Tb-rich shell were lower relatively reduced.After grain boundary modification,the flat,thin,and continuous Nd-rich phase was formed be-tween the grain along the vertical TEM analysis showed that C-axis diffusion magnets,which isolated the demagnetization cou-pling between the two main phases and greatly improved the coercivity of the magnets.
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