▎ 摘　　要

The effects of oxygen content in graphene nanoplatelets (GNPs) on the microstructure and magnetic properties of hot-deformed (HDed) Nd-Fe-B magnets were investigated in this work. The GNPs were heat treated at 500 degrees C to effectively reduce the oxygen content from 27000 ppm (GNP-R) to 7768 ppm (GNP-H). Compared with adding the same amount of GNP-R, the GNP-H doped magnet possessed finer and better texture grains at the contact interface of original powders. The coercivity of GNP-H doped magnet was enhanced from 14.16 kOe to 16.62 kOe, and the remanence increased from 13.18 kGs to 13.61 kGs. Owing to the high thermal conductivity of GNP-H doped magnet, the heat transferred between the grains more quickly and thus restraining the grain growth. Therefore, the GNP-H doped magnet got a higher coercivity. The observation of microstructure revealed that the adsorbed oxygen on the surface of GNP-R reacted with Nd-rich phase. It would result in the oxidation of Nd-rich phase and the decreasing of Nd-rich phase at the grain boundaries. Because of inadequate liquid Nd-rich phase, the Nd2Fe14B grains were difficult to complete the dissolution-reprecipitation. Consequently, a high oxygen environment would deteriorate the orientation of grains.