Development of trapezoid-shaped Nd-Fe-B die-upset magnets by preform method

Basic investigations to apply the rapid quenched Nd-Fe-B die-upset technique to fabricate trapezoid-shaped magnets with high energy product were undertaken. Stress around the magnets with indentations during die-upsetting was evaluated by computer simulation. The dimensions of preform shape for isotropic consolidated magnets before hot deformation were determined from compression tests using an aluminum alloy. Hot deformation to obtain the final trapezoid-shape was divided into two steps. The total reduction in height during compression exceeded approximately 72%, and the finished magnets had no cracks. By this method, trapezoid-shaped die-upset magnets with a high energy product of >320 kJ/m/sup 3/ have been fabricated.<
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