Study on the microstructure and properties of Nd-Fe-B regenerated magnet by adding Ho69.3Ni30.7 alloy at grain boundary

Abstract The Nd-Fe-B regenerated magnets are prepared by adding low melting point Ho69.3Ni30.7 alloy at the grain boundary, and the microstructure, structure and overall performance of the Nd-Fe-B regenerated magnets are studied. The results show that the addition of Ho69.3Ni30.7 alloy to grain boundary can optimize the distribution of grain boundary phase, accompanied by the formation of clear and continuous grain boundary phase, which weakens the exchange coupling effect between the adjacent main phases. Meanwhile, the coercivity of the regenerated magnet increases with the increase of Ho69.3Ni30.7 alloy content. The optimal coercivity (16.35 kOe) was obtained at 2 wt% Ho69.3Ni30.7 additions, and the coercivity increased by 1.24 kOe (8.2%) compared with the initial magnet (15.11 kOe). In addition, with the addition of Ho69.3Ni30.7 alloy, the curie temperature of Nd-Fe-B regenerated magnet increased from 303.2℃ to 305.6℃. The reflection loss of regenerated magnet reached -26.42 dB when the amount of 2 wt% Ho69.3Ni30.7 was added, which greatly improved the absorbing performance of the regenerated magnet. Finally, the secondary utilization of waste Nd-Fe-B magnets was realized.