Nd-Dy-Fe-B系焼結磁石の強磁場中熱処理と保磁力

概要

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The effect of a high magnetic field on coercivity was investigated in the annealing process for sintered NdFe-B magnets containing Dy 10wt.%. In a sample containing Cu 0.13wt.%, a coercivity value H_c of 36 kOe was obtained for an annealing temperature T_a of 475℃ under an annealing field H_a of 140 kOe. This value of H_c is 20% larger than that for the control sample (T_a=475℃ and H_a=0). In samples without Cu, H_c values were considerably smaller (<27 kOe) and no such enhancement of the coercivity by the magnetic fields was observed. The DSC curves exhibited a marked endothermic reaction just below 500℃ only for samples containing Cu. This temperature is attributed to a eutectic point of Nd_<70>Cu_<30>. A possibility of field-induced alignment of Nd-rich grains in a matrix of Nd-Cu liquid is discussed; this would be closely related to the coercivity enhancement.
社団法人日本磁気学会の論文
2006-07-01