METHOD FOR PRODUCING ALLOY CAST SLAB FOR RARE EARTH SINTERED MAGNET

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Provided are alloy flakes for rare earth sintered magnet, which achieve a high rare earth component yield after pulverization with respect to before pulverization and a uniform particle size after pulverization, and a method for producing such alloy at high energy efficiency in an industrial scale. The method includes (A) preparing an alloy melt containing R composed of at least one element selected from rare earth metal elements including Y, B, and the balance M composed of Fe, or of Fe and at least one element selected from transition metal elements other than Fe, Si, and C, (B) rapidly cooling/solidifying the alloy melt to not lower than 700° C. and not higher than 1000° C. by strip casting with a cooling roll, and (C) heating and maintaining, in a particular temperature range, alloy flakes separated from the roll by rapid cooling and solidifying in step (B) before the flakes are cooled to not higher than 500° C., to obtain alloy flakes having a composition of 27.0 to 33.0 mass % R, 0.90 to 1.30 mass % boron, and the balance M.