Effect of Nd Substitution for Mischmetal on Magnetic Properties in (MM,Nd)-Fe-B Ribbons

摘要

Mischmetal-based permanent magnets of (MM,Nd)(12)Fe82B6 were prepared by melt-spinning method via varying the relative content of mischmetal and Nd. The coercivity is low, and the squareness of hysteresis loop is poor in MM12Fe82B6 ribbons. The x-ray diffraction pattern, maximum of delta m value as well as the temperature dependence of magnetization indicates that the partial substitution of Nd for MM could improve the crystallinity in the mischmetal-based magnets, and both the coercivity and squareness of hysteresis loop increase with Nd substitution for mischmetal. The increase of squareness should be partially attributed to the improvement in the crystallinity of R2Fe14B crystal phase. For more than 4 at.% Nd substitution the coercivity is not less than that in corresponding (Ce,Nd)-based magnets, and the coercivity of 7.81 kOe and the maximum energy product of 15.41 MGOe were obtained in MM8Nd4Fe82B6 ribbons. These investigations show that it is reasonable to use the low cost mischmetal to prepare the resource-saving rare-earth magnets, and that optimizing the addition amount of Nd is necessary to improve the crystallinity and enhance the magnetic properties.