Method for producing rare-earth magnet

A method for producing a rare-earth magnet, comprising:

• a first step of producing a sintered body with a structure including a main phase and a grain boundary phase, the sintered body consists of Nd, Pr, Fe, B, and M wherein the sintered body has a composition expressed by a formula:
• (Nd1-xPrx)aFebBcMd where B represents boron, M is at least one selected from the group consisting of Ti, Ga, Zn, Si, Al, Nb, Zr, Ni, Co, Mn, V, W, Ta, Ge, Cu, Cr, Hf, Mo, P, C, Mg, Hg, Ag, and Au, 0<x <0.5, 12≤a≤20, b=100−a−c−d , 5≤c ≤20, and 0≤d ≤20, and 0≤d ≤3 all by at %;
• a second step of applying hot deformation processing to the sintered body to produce a precursor of a rare-earth magnet;
• and
• a third step of providing a Nd-Cu alloy consisting of Nd and Cu on a surface of the precursor of the rare-earth magnet and then heat treating the precursor of the rare-earth magnet to diffuse and infiltrate a melt of the Nd-Cu alloy into the grain boundary phase of the precursor of the rare-earth magnet to produce a rare-earth magnet,
• wherein the rare-earth magnet has a main phase with a core-shell structure, wherein a composition of a shell formed around the core is a (NdPr)FeB phase, in which a content of Nd is more than a content of Pr,
• wherein a proportion of the main phase to the entire structure of the rare-earth magnet being is 95% or greater by volume percent, and
• the rare-earth magnet has a coercivity at 200° C. of higher than 4.8 kOe and less than 5.6 kOe.