Electrical resistivity and magnetic properties of Nd-Fe-B alloys produced by melt-spinning technique

The electrical resistivity and magnetic properties of Nd-Fe-B alloys produced by the melt-spinning technique were examined. The wheel speed, which is closely associated with the cooling rate, was varied in the production of the melt-spun ribbons. The resultant melt-spun ribbons had various microstructures ranging from dendrite to equiaxed grains, and finally to an amorphous structure, depending on the wheel speed. It was found that both the resistivity and coercivity of the melt-spun ribbons were strongly dependent on the wheel speed. The maximum resistivity of 3.15 μΩ m was achieved in a melt-spun ribbon primarily consisting of the amorphous phase with a small amount of the Nd2Fe14B phase, while the highest coercivity of 1.97 MA/m was achieved in a melt-spun ribbon primarily consisting of the Nd2Fe14B phase with a small amount of the amorphous phase. The relationships among the cooling rate, microstructure, resistivity, and coercivity of the Nd-Fe-B alloys were determined.