R-Fe-B sintered magnetoplasts and their particle diffusion treatment methods

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Disclosed is an R-Fe-B sintered magnet. The R-Fe-B sintered magnet is obtained by performing an HR grain boundary diffusion treatment on an R-Fe-B sintered green body, wherein the green body at least comprises 28 wt% to 33 wt% of R, which is at least one rare earth element including Nd; 0.83 wt% to 0.96 wt% of B; and 0.3 wt% to 1.2 wt% of M. A grain boundary diffusion direction is perpendicular to a magnetization direction, and along the diffusion direction, the ratio of the contents of HR between any two points in a diffusion plane, between which the distance is not more than 500 μm, is 0.1 to 1.0. Further disclosed in the present invention is a grain boundary diffusion treatment method, whereby grain boundary diffusion of a diffusion source occurs along a direction perpendicular to c axis. In addition, local demagnetization is efficiently controlled, a diffusion effect is enhanced, a manufacturing procedure is simplified, deformation factors are eliminated, and material utilization is greatly increased.