Effect of small dysprosium additions on the coercivity of melt-spun Nd-Fe-C alloys

The influence of small dysprosium additions on the microstructural development and the coercivity of melt-spun iron-rich Nd/sub 15-x/Dy/sub x/Fe/sub 77/C/sub 8/ (x=0.5-5.0) alloys was investigated. By X-ray diffraction analysis, it was, found that amorphization of as-spun ribbons spun at 25 m/s was promoted by increasing the Dy addition. The ribbons became fully amorphous with 5.0 at.% Dy. Small additions of Dy not only improved the thermal stability of Nd/sub 2/Fe/sub 14/C, which was obtained by a proper annealing, but also enhanced the grain refinement of the Nd/sub 2/Fe/sub 14/C, resulting in a large increase in coercivity. When the addition of Dy was more than 3.0 at.%, the intrinsic coercivities of more than 17 kOe, which would be the highest coercivity ever obtained from iron-rich Nd-Fe-C alloys, were easily obtained after annealing 10 min. at 800-900/spl deg/C.