Abstract：Various types of Nd- Fe- B sintered magnets were prepared by adjusting wheel speed of strip casting and rotation speed of filter wheel in jet- milling machine on the condition of Dy- free and uniform composition and the relationship between critical parameters including columnar grain width, powder size, ultimate grain size and coercivity was investigated. It was discovered that refinement and homogenization of the casted strips are the critical precondition for those of jet- milled powder, and ideal grain refinement of the magnet was possible only when refinement of strips were combined with high rotation filtering jet- milling. Corresponding average grain diameter was 3. 76μm low and the coercivity was 1339kA/m high. Grain refinement possibly reduces the superficial defect area and smoothen the boundary of the grain, and that decreases the possibility of anti- magnetization and local magnetostatic interaction field, increasing the coercivity ultimately.
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2018, Vol. 25 
