High performance nanostructured Nd–Fe–B fine powder prepared by melt spinning and jet milling

Isotropic Nd–Fe–B nanocrystalline fine powders with particle size in the range of 1–10 μm have been developed using melt spinning and jet milling. The processing steps primarily consist of melt spinning Nd–Fe–B alloy to obtain ribbons with 25–50 μm thickness, crushing the ribbon to obtain coarse powder with average particle size of about 200 μm, and jet milling the coarse powder to obtain fine powder with average particle size of about 5–6 μm. The effects of jet milling conditions on powder particle size, microstructure, and magnetic properties were systematically studied. For a magnet alloy nominally composed of Nd11.9(Fe0.93Co0.07)82.6B5.5, a particulate yield of D10=2 μm, D50=6 μm, and D90=11 μm and magnetic properties of Br=8.82 kG, Hci=9.5 kOe, and (BH)max=15.3 MGOe have been achieved in melt-spun and jet milled fine powders. The combined advantage of small particle size and high magnetic performance will make the Nd–Fe–B fine powder an attractive candidate for applications such as magnetic fluids, inks, micromachines, and flexible sheets.

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