Process for production of R-Fe-B-based rare earth sintered magnet, and steam control member

摘要

A sintered R—Fe—B based rare-earth magnet body 1 including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is Nd and/or Pr, as a major rare-earth element R is provided. A bulk body 2 including a heavy rare-earth element RH, which is at least one of Dy, Ho and Tb is also provided. The sintered magnet body 1 and the bulk body 2 are arranged in a processing chamber 4 with a vapor control member 3 interposed between the sintered magnet body 1 and the bulk body 2. And the inside of the processing chamber 4 is heated to a temperature of 700° C. to 1000° C., thereby diffusing the heavy rare-earth element RH inside the sintered magnet body 1 while supplying the heavy rare-earth element RH from the bulk body 2 to the surface of the sintered magnet body 1 via the vapor control member 3.

主权项

1. A method for producing a sintered R—Fe—B based rare-earth magnet, the method comprising the steps of:
providing a sintered R—Fe—B based rare-earth magnet body including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R; providing a bulk body including a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb; arranging the sintered R—Fe—B based rare-earth magnet body and the bulk body in a processing chamber with a vapor control member interposed between the sintered R—Fe—B based rare-earth magnet body and the bulk body; and heating the inside of the processing chamber to a temperature of 700° C. to 1000° C., thereby diffusing the heavy rare-earth element RH into the sintered R—Fe—B based rare-earth magnet body while supplying the heavy rare-earth element RH from the bulk body to the surface of the sintered R—Fe—B based rare-earth magnet body via the vapor control member, wherein the vapor control member includes: an upper surface and a lower surface; a plurality of openings, which communicate between the upper and lower surfaces; and a wall portion, which defines the openings, and wherein the wall portion has a thickness of 0.5 mm or less, each said opening of the vapor control member has a depth of 1 mm to 10 mm, D/A is equal to or smaller than 8 mm−1, where each said opening of the vapor control member has an area of A [mm2] and a depth of D [mm], and in the step of heating, a gap between the sintered R—Fe—B based rare-earth magnet body and the vapor control member is set to be within a range of 0 mm to 10 mm, a gap between the vapor control member and the bulk body is set to be within a range of 0 mm to 10 mm, and a gap between the sintered R—Fe—B based rare-earth magnet body and the bulk body is set to be 10 mm or less.