METHOD OF PRODUCING R-T-B-BASED RARE EARTH MAGNET POWDER, R-T-B-BASED RARE EARTH MAGNET POWDER, AN

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PROBLEM TO BE SOLVED : To provide a method of producing R-T-B-based rare earth magnet powder having excellent coercive force and also having high residual magnetic flux density. SOLUTION : In a method of producing R-T-B-based rare earth magnet powder by HDDR (Hydrogenation-Decomposition-Desorption-Recombination) treatment, a raw material alloy for the R-T-B-based rare earth magnet powder comprises R (R : one or more rare earth elements including Y), T (T : Fe, or Fe and Co) and B (B : boron), and has a composition comprising R in an amount of 12.0 atom% or more and 17.0 atom% or less, and B in an amount of 4.5 atom% or more and 7.5 atom% or less; a DR step in the HDDR treatment includes a preliminary evacuation step and a complete evacuation step; and a rate of pressure reduction caused by evacuation in the preliminary evacuation step is set to 1 kPa/min or more and 30 kPa/min or less to produce the R-T-B-based rare earth magnet powder. SELECTED DRAWING : None COPYRIGHT : (C)2017, JPO&INPIT