The invention discloses a
crystal boundary
diffusion method for improving the coercive force and the
thermal stability of a
neodymium-iron-
boron magnet, and belongs to the field of
rare earth permanent
magnet materials. According to the method, a
quaternary alloy Dy-Ni-Al-Cu with a
low melting point is used as a
diffusion source and melted and prepared into a rapid-hardening strip, after coarse breaking, the
strip casting is laid around the
neodymium-iron-
boron magnet, and by the adoption of a heat treatment method, the rapid-hardening strip diffuses and enters the magnet along the
crystal boundary. After the
processing, the coercive force of the magnet is significantly improved, and the
magnetic energy product is improved to a certain extent; meanwhile, since the temperature of the
diffusion treatment is low,
energy consumption can be reduced, the cost can be lowered, and Nd2Fe14B
crystal grains can be prevented from growing up; compared with a
coating and magnetron
sputtering method, the crystal boundary diffusion method omits a
powder preparing and
coating process in a
coating technology and a thin film preparing process in a magnetron
sputtering technology. After the technology
processing of the crystal boundary diffusion method, the
neodymium-iron-
boron magnet with the high coercive force and the high
thermal stability is finally obtained.