METHOD FOR MANUFACTURING R-T-B SINTERED MAGNET
2022-06-06
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[Problem] There is provided a method of producing a sintered R-T-B based magnet in which even the intergranular grain boundaries in the magnet interior can be made thick, which does not allow coercivity improvement effects to be significantly undermined even after a surface grinding, and which has high coercivity without the use of heavy rare-earth elements.
[Solution] It includes : a step of providing an R1-T1-A-X (where R1 is mainly Nd; T1 is mainly Fe; A is at least one of Ga, Ti, Zr, Hf, V, Nb and Mo; and X is mainly B) based sintered alloy compact which is mainly characterized in that a molar ratio of Ti/(X-2A) is not less than 13; a step of providing an R2-Ga—Cu (where R2 is mainly Pr and/or Nd and accounts for 65 mol % and not more than 95 mol %; and Cu/(Ga+Cu) is not less than 0.1 and not more than 0.9 by mole ratio) based alloy; and a step of, while allowing at least a portion of the R2-Ga—Cu based alloy to be in contact with at least a portion of a surface of the R1-T1-A-X based sintered alloy compact, performing a heat treatment at a temperature of 450° C. to 600° C.