Manufacturing method of alloy cast for rare earth sintered magnet, alloy cast for rare earth sintered magnet, and rare earth sintered magnet

摘要

The invention provides a method for producing alloy flakes for rare earth sintered magnets, which makes uniform the intervals, size, orientation, and shape of the R-rich region and the dendrites of the 2-14-1 phase, which inhibits formation of chill, and which produces flakes that are pulverized into powder of a uniform particle size in the pulverization step in the production of a rare earth sintered magnet, and that are pulverized into powder compactable into a product with a controlled shrink ratio, and alloy flakes for a rare earth sintered magnet obtained by the method, and a rare earth sintered magnet having excellent magnetic properties. The present method includes preparing an alloy melt of a composition consisting of R of rare earth metal elements and the balance M including B and Fe, and supplying and solidifying the alloy melt on a cooling roll, wherein the roll has on its surface linear nucleation inhibiting portions for inhibiting formation of dendrites or the like, and nucleating portions for formation of the dendrites, and wherein the inhibiting portions have a region with a width of more than 100 m.