Low field magnetic properties of Nd50Fe40Si10-xAlx melt-spun and bulk amorphous alloys

Glass-forming ability and low field magnetic properties of Nd50Fe40Si10-xAl x (x = 0-10) melt-spun ribbons and cast rods are investigated in the temper ature range 5-600 K. The dependence of the coercive field on the thickness and preparation method is ascribed to the existence in the amorphous matrix of very small Fe-Nd-based ferromagnetic clusters, which can not be detecte d by XRD measurements, the size of which approaches to a single magnetic do main. Coercivity increases substantially at reduced temperatures even in lo w fields. The development in Nd-Fe-based bulk amorphous alloys of two diffe rent types of magnetic order, ie. short-range spin-glass-like order and lon g-range ferromagnetic order is revealed by zero-field-cooled and held-coole d magnetization measurements.