Patent ID: 9721724
Date: 2017-08-01
CPC Classifications: C22C,H01F

Claim:
1. A method for producing a sintered R-T-B based magnet, the method comprising the steps of: forming a stack of RH diffusion sources (which are made of a metal or alloy, of which at least 80 at % is a heavy rare-earth element RH that is at least one of Dy and Tb) and sintered R-T-B based magnet bodies (where R is at least one of the rare-earth elements and T is at least one of the transition metal elements and always includes Fe) by stacking the diffusion sources and the magnet bodies alternately with a holding member having openings interposed; carrying out an RH supply-diffusion process by loading the stack into a process vessel and creating an atmosphere with a pressure of 0.3 Pa to 50 Pa and a temperature of 800° C. to 950° C. within the process vessel, wherein throughout the RH supply-diffusion process, the pressure is maintained between 0.3 Pa to 50 Pa and the temperature is maintained between 800° C. to 950° C.; and carrying out an RH diffusion process by creating an atmosphere with a pressure of 200 Pa to 2 kPa and a temperature of 800° C. to 950° C. in the process vessel after the RH supply-diffusion process has been carried out, wherein throughout the RH diffusion process, the pressure is maintained between 200 Pa to 2 kPa and the temperature is maintained between 800° C. to 950° C.