Production method of rare earth magnet

A production method of a rare earth magnet, comprising:

• forming a metal zinc-containing coating on a particle surface of a magnetic powder by using a zinc-containing powder having an oxygen content of 5.0 mass % or less, wherein the magnetic powder contains samarium, iron and nitrogen and includes a magnetic phase having at least either one of Th2Zn17 type and Th2Ni17 type crystal structures to obtain a coated magnetic powder,
• mixing a binder powder having a melting point not higher than the melting point of the coating with the coated magnetic powder to obtain a mixed powder,
• compression-molding the mixed powder at a pressure of 50 MPa or more to obtain a green compact and,
• pressure-sintering the green compact at T1° C. or more and (T2−50° C.) or less, wherein a temperature at which a peak disappears in an X-ray diffraction pattern of the binder powder is denoted as T1° C. and a temperature at which the magnetic phase decomposes is denoted as T2° C.,
• wherein a particle diameter of the magnetic powder is 1 μm or more and 10 μm or less,
• wherein the binder powder is one or more powders selected from the group consisting of an aluminum-lanthanum-copper-based alloy-containing powder, which are different materials from the material of the metal zinc-containing coating,
• wherein the pressure of the pressure-sintering is 700 MPa or more and 5,000 MPa or less,
• wherein the metal zinc-coating reduces friction on the particle surface of the samarium-iron-nitrogen-based magnetic powder during the compression, an αFe phase on the particle surface of the magnetic powder reacts with the metal zinc of the coating during pressure-sintering to form a zinc-iron phase on the particle surface of the magnetic powder, and the binder mutually bonds the magnetic powder particles through the zinc-iron phase during the pressure-sintering,
• wherein in a cross-section of a particle of the coated magnetic powder, a percentage of the length of a portion where the particle surface of the magnetic powder is covered by the coating, relative to an entire circumferential length of the particle surface of the magnetic powder, is 90% or more, and
• wherein the rare earth magnet has a coercive force of at least approximately 931 kA/m.