Process for producing R-T-B-based rare earth magnet particles, R-T-B-based rare earth magnet particles, and bonded magnet

A process for producing R-T-B-based rare earth magnet powder by HDDR (Hydrogenation-Decomposition-Desorption-Recombination) treatment, in which a raw material alloy for the R-T-B-based rare earth magnet powder comprises 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 comprising R in an amount of not less than 12.0 atom % and not more than 17.0 atom %, and B in an amount of not less than 4.5 atom % and not more than 7.5 atom %;

• the HDDR treatment comprises:
• an HD (Hydrogenation-Decomposition) step using a furnace,
• an atmosphere replacing step comprising replacing an inside atmosphere of the furnace with Ar, and subsequently
• a DR (Desorption-Recombination) step comprising a preliminary evacuation step and a complete evacuation step;
• and a rate of pressure reduction caused by evacuation in the preliminary evacuation step is always held constant or changed during the evacuation within a range of not less than 1 kPa/min and not more than 6.5 kPa/min, wherein a vacuum degree after the evacuation in the preliminary evacuation step is not less than 1.0 kPa and not more than 5.0 kPa, wherein the raw material alloy comprises at least Nd and Pr as R (wherein R represents at least one rare earth element including Y), and a content of Pr in R is not less than 10 atom % and not more than 80 atom %, wherein the maximum energy product ((BH)max) of the R-T-B-based rare earth magnet powder is not less than 296 kJ/m3.