HREE free sintered R-Fe-B magnets and manufacturing method thereof

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The present invention relates to a R-Fe-B type sintered magnet, wherein a R_2Fe_14B crystal grains (R = La, Ce, Nd, Pr, Pm, Sm, Eu, or Nb) including light rare earth elements forms a main phase, and the magnet composed of a microstructure in which R-rich phase (R = La, Ce, Nd, Pr, Pm, Sm, Eu, or Nb) including light rare earth elements surrounds the periphery of the crystal grains, and the magnet includes a second phase including high melting point metal elements selective for grain boundary formed by the R_2Fe_14B crystal grains, and has a feature where a contiguity between two adjacent R_2Fe_14B crystal grains is less than or equal to 50%, and R-Fe-B type sintered magnet forms a high melting point metal on a surface of a R-Fe-B type raw material powder, to distribute fine second phase at grain boundaries of an entire sample. As such, it is possible to limit effectively a microstructure of the sintered magnet; and not does it overcome the limitations of the physical and magnetic characteristics of a conventional R-Fe-B type sintered magnet, but may also be free from heavy rare earth element supply problems and have an advantage of reducing costs.COPYRIGHT KIPO 2016