Magnetic properties and microstructure of sintered NdFeB magnets with intergranular addition of Ni powders

Abstract This paper aims to improve the magnetic properties of sintered Nd Fe B magnet. Ni powders were added to the Nd Fe B magnet through intergranular addition, and their effects on the microstructure and magnetic properties of the magnet were investigated. By adding a proper amount of Ni (0.3 wt%), the intrinsic coercivity H cj of Nd Fe B magnet is significantly improved with only a slight decrease in the remanence B r and the maximum energy product ( BH ) max . The microstructural and compositional analyses reveal that Ni atoms not only enter the matrix phase but also concentrate in the intergranular regions either as Ni-containing Nd-rich phase or as Ni particles. This is consistent with the thermodynamic calculation results. Furthermore, a sintering mechanism of magnet with intergranular addition of Ni powders is tentatively proposed. These results may provide a reference for improving the magnetic properties of sintered Nd Fe B magnets.