Study on the process of NdFeB magnet prepared by spark plasma sintering

NdFeB magnet was prepared by spark plasma sintering technique. Effects of sintering process and heat treatment on the magnetic properties, dimensional precision as well as density were studied. Magnetic properties, microstructure and constituents were investigated by means of B-H loop-line instrument, SEM. It is found that the microstructure of SPS NdFeB magnet is quite different, the grain size of Nd₂Fe₁₄B is fine and uniform while the distribution of the Nd-rich phase is heterogeneous. The optimal magnetic properties of the SPS NdFeB magnet obtained so far are of a maximum energy product of 240 kJ/m³, a coercive force of 1160 kA/m. The density of the magnet reaches 7.58 g/cm³ as well as the dimensional precision of the magnets is about 20μ m.