公开(公告)号：US11688534B2

公开(公告)日：2023-06-27

申请号：US15010539

申请日：2016-01-29

Applicant: TODA KOGYO CORP.

Inventor： Shohei Kaneko ,  Kuniyoshi Shigeoka ,  Nobuhiro Katayama ,  Koichiro Morimoto

IPC: H01F1/08 ,  B22F9/02 ,  H01F1/053 ,  C22C38/14 ,  C22C38/10 ,  C22C38/06 ,  C22C38/00 ,  H01F1/057

CPC classification number: H01F1/083 ,  B22F9/023 ,  C22C38/002 ,  C22C38/005 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  H01F1/0573 ,  B22F2201/013 ,  B22F2203/13 ,  B22F2301/355 ,  B22F2998/10 ,  C22C2202/02 ,  H01F1/0572 ,  H01F1/0578

Abstract: A process for producing R-T-B-based rare earth magnet powder having excellent coercive force and high remanent flux density. A process for producing R-T-B-based rare earth magnet powder by HDDR treatment, in which a raw material alloy for the R-T-B-based rare earth magnet powder includes R (wherein R represents at least one rare earth element including Y), T (wherein T represents Fe, or Fe and Co) and B (wherein B represents boron), and has a composition including R in an amount of between 12.0 atom % and 17.0 atom %, and B in an amount of between 4.5 atom % and 7.5 atom %; the HDDR treatment includes a DR step including a preliminary evacuation step and a complete evacuation step; and a rate of pressure reduction caused by evacuation in the preliminary evacuation step is not less than 1 kPa/min and not more than 30 kPa/min.