METHOD FOR MANUFACTURING R-T-B BASED SINTERED MAGNET

PROBLEM TO BE SOLVED : To provide a method for manufacturing an R-T-B based sintered magnet having high Br, HcJ and Hk/HcJ without using RH.SOLUTION : Disclosed is a method for manufacturing an R-T-B based sintered magnet which includes R of 27.5-34.0 mass% (where R is at least one kind of rare earth elements, including at least one of Nd and Pr necessarily), B of 0.85-0.93 mass%, Ga of 0.2-0.7 mass%, Cu of 0.05-0.7 mass%, Al of 0.05-0.4 mass% and T of 61.5 mass% or more (where T represents Fe and Co, and the Fe accounts for 90% or more of T on a mass percentage basis), and satisfies the following expressions : (1)([T]-72.3[B]>0); and (2)(([T]-72.3[B])/55.85<13[Ga]/69.72). The method comprises : a step of preparing an R-T-B based alloy; a hydrogen pulverizing step of heating the alloy under a hydrogen pressurized atmosphere at 5-350°C for hydrogen embrittlement thereof and then, heating the resultant alloy at 750-850°C to perform a dehydrogenation treatment in a reduced-pressure atmosphere of 3000 Pa or less or an inert gas atmosphere; a fine pulverization step of pulverizing coarse powder of the alloy; a shaping step of shaping the resultant alloy powder into a compact; and a sintering step of sintering the compact.SELECTED DRAWING : NoneCOPYRIGHT : (C)2018, JPO&INPIT