RARE EARTH-TRANSITION METAL-NITROGEN BASED MAGNET FINE POWDER, AND METHOD FOR MANUFACTURING THE SAM

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PROBLEM TO BE SOLVED : To provide rare earth-transition metal-nitrogen based magnet fine powder having an improved magnetic property and excellent surface stability by finely pulverizing magnet powder within a particular particle size range and controlling an amount of remaining P(phosphorus), and a method which enables efficient manufacture of such rare earth-transition metal-nitrogen based magnet fine powder by pulverizing magnet coarse powder with a particular device under a particular condition.SOLUTION : Rare earth-transition metal-nitrogen based magnet fine powder is produced by finely pulverizing magnet alloy powder with a media stirring mill which uses at least pulverization media having a diameter of 0.1-1 mm together with phosphoric acid. The magnet alloy powder includes 23.0-25.0 mass% of rare earth elements and 3.0-3.6 mass% of N with the balance including Fe, and is manufactured by a reduction diffusion method. In the rare earth-transition metal-nitrogen based magnet fine powder, the average particle diameter (D50) is over 1.7 μm up to 2.5 μm; the rate of particles having a particle size of no more than 1 μm is less than 20%; and the content of P is 0.6 mass% or less in terms of phosphorus element.