Rare earth permanent magnet and preparation method of rare earth permanent magnet

The invention discloses a rare earth permanent magnet and a preparation method of the rare earth permanent magnet. The rare earth permanent magnet is characterized in that: a volume diffusion phenomenon of heavy rare earth elements occurs on material of the rare earth permanent magnet from the surface of the magnet along the magnetic aligning direction to the depth of 5 microns to 100 microns of the interior of the magnet so that a volume diffusion layer area is formed; the volume diffusion area is divided into magnet units with the size of 10*100*5 microns; and concentration difference of heavy rare earth elements of magnet units at all positions in a volume diffusion layer is below 0.5 at%. The invention provides a sintered Nd-Fe-B magnet equipped with great intrinsic coercivity Hcj without affecting product remanent magnetism Br and maximum magnetic energy product (BH) max.In the preparation method of the rare earth permanent magnet, a blank magnet coating heavy rare earth slurries is subjected to microwave heat-treatment in the vacuum condition.The method can effectively increase heating efficiency, shorten heat-treatment time, reduce energy consumption and lower production cost of the magnet.