R a-T a-B based rare earth magnet powder, R a-T a-B based rare earth magnet powder production, and

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The present invention relates to a process for producing R-T-B-based rare earth magnet particles by HDDR treatment which comprises a first stage HD step of heating particles of a raw material alloy having a composition comprising R in an amount of not less than 12.5 atom% and not more than 14.3 atom%, B in an amount of not less than 4.5 atom% and not more than 7.5 atom% and Co in an amount of not more than 10 atom% to a temperature range of not lower than 770°C and not higher than 820°C in an inert atmosphere or in a vacuum atmosphere and then replacing the atmosphere with a hydrogen-containing gas atmosphere in which the raw material alloy particles are held in the same temperature range; and a second stage HD step of heating a material obtained in the first stage HD step again to a temperature range of not lower than 830°C and not higher than 870°C in which the material is held in the hydrogen-containing gas atmosphere.