Studies of New YDy-Based<tex>$hboxR_2hboxFe_14hboxB$</tex>Magnets for High Temperature Performance<tex>$(hboxR=hboxY+hboxDy+hboxNd)$</tex>

The effect of Nd substitution on microstructure and magnetic properties in [Nd/sub x/(YDy)/sub 0.5(1-x)/]/sub 2.2/Fe/sub 14/B ribbons melt-spun at 22 m/s has been systematically studied. As-spun ribbons with low Nd content consist of 2 : 17 and 2 : 14 : 1 phases in an amorphous matrix, while as-spun ribbons with high Nd contain 2 : 14 : 1 and Fe phases in the amorphous matrix. After annealing at 700/spl deg/C for 15 min, all of the ribbons exhibit only a single 2 : 14 : 1 phase in their X-ray diffraction patterns. Nd substitution can improve the maximum energy product of annealed ribbons but deteriorate the temperature stability of the ribbons. Increasing Nd (x) from 0 to 0.8, decreases coercivity from 22 to 13.5 kOe, but increases the maximum energy product from 5.87 to 11.2 MGOe. The temperature coefficients for remanence and coercivity increase from -0.045/spl deg/C to -0.106 %//spl deg/C, and -0.306 to -0.38 %//spl deg/C, respectively for the same substitution range. Transmission electron microscope microstructures show that the samples with less Nd content exhibit a more uniform distribution of grains. Their average grain size is about 40 nm. The studied results show that the YDy-based R/sub 2/Fe/sub 14/B magnets are very promising for high-temperature performance.