Method for producing r-t-q system sintered magnet

A method for producing a sintered R-T-Q based magnet, comprising:

• a pulverization step of pulverizing an R-T-Q based magnet alloy (R is at least one of rare-earth elements and contains at least one of Nd and Pr with no exception, T is at least one selected from the group consisting of elements of Fe, Co, Ni, Al, Mn, Cr and V, and T contains Fe with no exception, and Q is a total of B and C) to form an alloy powder;
• a powder pressing step of producing a compact of the alloy powder;
• and
• a sintering step of sintering the compact to form a sintered R-T-Q based magnet,
• wherein a content of R in the sintered R-T-Q based magnet is not higher than 30 mass % of the entirety of the sintered R-T-Q based magnet, a content of B is not higher than 0.90 mass % of the entirety of the sintered R-T-Q based magnet, and a total content of B and C is not higher than 0.99 mass %,
• wherein the pulverization step includes a hydrogen pulverization step and a fine pulverization step,
• wherein the hydrogen pulverization step includes:
• a hydrogen occlusion step of causing the R-T-Q based magnet alloy to occlude hydrogen at a temperature that is not higher than 200° C. in a processing chamber, and
• a dehydrogenation step of discharging hydrogen from the processing chamber and heating the alloy to a range that is not lower than 80° C. and not higher than 350° C. to perform a dehydrogenation process, thus to form a coarse-pulverized powder having a content of hydrogen that is not lower than 1000 ppm and not higher than 2000 ppm, and
• wherein the fine pulverization step includes a step of pulverizing the coarse-pulverized powder to obtain a fine powder having a median diameter d50 that is not longer than 3.5 μm.