R-T-B BASED SINTERED MAGNET

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PROBLEM TO BE SOLVED : To provide an R-T-B based sintered magnet having a high Br and a high HcJ without using RH such as Dy as far as possible (or with an amount of use of RH minimized). SOLUTION : An R-T-B based sintered magnet comprises R of 27.5% or more and 34.0% or less (R is at least one kind of rare earth elements, always including at least one of Nd and Pr), B of 0.85% or more and 0.93% or less, Ga of 0.20% or more and 0.75% or less, Sn of 0.05% or more and 0.60% or less, Cu of 0.05% or more and 0.70% or less, Al of 0.05% or more and 0.40% or less, and T of 61.5% or more (T represents Fe and Co, and by mass percentage, Fe accounts for no less than 90% of T), which are represented by mass%. The R-T-B based sintered magnet satisfies the following requirements (1) to (4) : 0<[T]-72.3×[B] (1); 0.2≤[Cu]/([Ga]+[Cu])≤0.5 (2); 0.5≤[Ga]/[Sn] (3); and 0.25≤[Ga]+[Sn]≤0.80 (4). SELECTED DRAWING : None COPYRIGHT : (C)2018, JPO&INPIT