Tailoring the mechanical anisotropy of sintered NdFeB magnets by Pr Cu grain boundary reconstruction

Abstract Pr 83 Cu 17 (wt%) grain boundary reconstruction was applied to prepare sintered NdFeB magnets. The effects of addition amount and annealing on the bending strength were investigated. The results show that Pr 83 Cu 17 can not only effectively enhance the bending strength, but also change the mechanical anisotropy in two directions parallel and perpendicular to c -axis. The bending strength perpendicular to c -axis reaches 404 MPa in 10 wt% addition magnet, higher than 348 MPa along parallel direction. This change is attributed to the preferred distribution of boundary phases, i.e., ductile (Nd,Pr) Fe Cu phase along perpendicular direction to c -axis and (Nd,Pr)-Fe phase along parallel direction. Moreover, the Cu migration during 480 °C annealing is found to be related to this boundary phase distribution.