METHOD OF PRODUCING R-T-B SINTERED MAGNET

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A method of producing an R-T-B sintered magnet is provided, said method including : 1) a step of preparing an R-T-B sintered magnet material that contains 27.5 to 34.0 mass% of R (R is at least one species of rare-earth elements and must include Nd), 0.85 to 0.93 mass% of B, 0.20 to 0.70 mass% of Ga, 0.05 to 0.50 mass% of Cu, and 0.05 to 0.50 mass% of Al with the remainder being T (T is Fe and Co, and at least 90% of T is Fe as the mass ratio) and unavoidable impurities and that satisfies formula (1) of [T]-72.3[B] > 0 and formula (2) of ([T]–72.3[B])/55.85 < 13[Ga]/69.72 ([T] is the T content in mass%, [B] is the B content in mass%, and [Ga] is the Ga content in mass%), by sintering a molding at a temperature of at least 1000°C and not more than 1100°C followed by the execution of (condition a) cooling to 500°C at not more than 10°C/minute or (condition b) a first heat treatment of holding at a first heat-treatment temperature of at least 800°C and not more than 950°C followed by cooling to 500°C at not more than 10°C/minute; and 2) a heat-treatment step of performing a second heat treatment by heating the R-T-B sintered magnetic material to a second heat-treatment temperature of at least 650°C and not more than 750°C and thereafter cooling to 400°C at at least 5°C/minute.