Crystallization behavior of melt-spun NdxFe93-xNb1B6 alloys

The crystallization behavior of NdxFe93-xNb1B6 melt-spun ribbons was investigated using calorimetric techniques. The crystallization products were identified by X-ray diffraction and thermomagnetic measurements. Samples with x greater than or equal to 10 crystallize directly from amorphous to a mixture of Nd2Fe14B and alpha-Fe phases. For 10< x <7, the final mixture of 2:14:1 and alpha-Fe phases is obtained through a two stage crystallization where the intermediate metastable Nd2Fe23B3 and Nd3Fe62B14 phases are produced at the initial crystallization. In samples with 7< x <4 the intermediate phase is Nd3Fe62B14. No metastable phases were observed in samples containing less than 3 at. % Nd although the calorimetric measurements indicated a two-step crystallization process.