Patent ID: 8845821
Filing Date: 2014-09-30
Classification: B22F,C22C,H01F

Abstract:
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 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 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.