MICROSTRUCTURE AND MAGNETIC HARDENING OF SINTERED NdFeB MAGNETS DOPPED WIHT Dy OR Dy_2O_3

摘要

The magnetic properties,microstructure and magnetic hardening of sintered(Nd_1-xDy_x)₁₆Fe_77.2B_6.8 and Nd₁₆Fe_77.2B_6.8+ywt-%Dy₂O₃ magnets have been stud-ied.As an addition of Dy to the magnet during smelting,Dy atoms may enter thematrix phase Nd₂Fe₁₄B,so as to enhance H_A,refine grains and improve boundary struc-ture,as well as to increase H_ciof the magnet.If Dy₂O₃ is added to powder materialprior to sintering,Dy atoms diffuse into the epitaxial layer of grains of matrix phasecausing enhancement of K′₁,also refinement of grains and improvement of boundarystructure.The NdFeB based permanent magnets with higher H_ci and greater（BH）_mmay be produced by adding about 2—3 wt-% Dy₂O₃ which make a favourable conditionfor lower cost.