MAGNETIC-BEHAVIOR OF RAPIDLY QUENCHED ND-DY-FE-B ALLOYS

The effects of wheel speed on the magnetic properties of melt-spun Nd1 3.5Dy3.7Fe75B7.8 alloys have been investigated. Structural characteriz ation has been carried out by X-ray diffraction and Scanning Electron Microscopy. Thermal demagnetization has been studied by thermomagnetic analysis. The as-quenched samples show the Curie temperature of an am orphous phase around 460 K besides the T(c) of the Nd2Fe14B1 phase at T(c) = 589 K. Hysteresis loops have been measured with a VSM with appl ied fields up to 2 T at room temperature. A dip in the second quadrant of the hysteresis loops confirms the presence of an amorphous phase i n the samples quenched at high speeds. After annealing the samples at 875 K for 4 min, the coercivity for the sample spun at 23 m/s has incr eased from 0.5 T to 1.55 T.