MAGNETIC-PROPERTIES OF AMORPHOUS ND4FE96-XBX ALLOYS AND INFLUENCES OF HEAT-TREATMENT ON THEIR HARD MAGNETIC-PROPERTIES

The magnetic moment and Curie temperature of amorphous Nd4Fe(96-x)B(x) alloys and the influence of heat treatment on its magnetic properties are studied. The Nd magnetic moment in the amorphous alloys is explained by a non-collinear structure. The Fe moment is found to decrease monotonically with increasing B concentration. The B-concentration dependence of the Curie temperature of the amorphous phase shows a maximum value of 622 K at about x = 25. The room temperature intrinsic coercive field (i)H(c) and maximum energy product (BH)max obtained under optimal annealing conditions increase at first with increasing x, show a narrow maximum value at about x = 18.5, and then decrease. For x = 18.5, the sample has a coercive field of (i)H(c) = 3 kOe and an energy product (BH)max = 13 MGOe. The hard magnetic properties in the crystallized NdFeB alloys with low Nd concentration originate from the presence of some hard magnetic Nd2Fe14B phases.