Optimization of grain boundary by Mo nano-powder to enhance the coercivity of NdFeB magnets

•Mo nano-powder as an auxiliary alloy has been added into NdFeB sintered magnets.•Mo nano-powder optimizes the microstructure of the magnet.•The dispersed distribution of the Mo element at the grain boundaries enhances the Hcj of the magnet. The Mo doped NdFeB magnets were prepared by the dual alloy method. Through transmission electron microscopy (TEM) and electron probe microanalyzer (EPMA), it is observed that the Mo element is mostly distributed at the grain boundary, which isolates the main phase grains, thus improving the intrinsic coercivity (Hcj) of the magnets. When the addition of Mo nano-powder is increased from 0 to1.0 wt%, the Hcj of the magnet is significantly improved. Especially, when the addition of Mo nano-powder is 0.8 wt%, the Hcj of the magnet is 138 kA/m higher than that of the magnet without Mo addition. The current research work shows that the Mo doped magnet prepared by the dual alloy method effectively improves the Hcj of NdFeB magnets, which has practical application value and theoretical significance for the research and development of high-performance NdFeB magnets.