Articles you may be interested inValve behavior of giant magnetoimpedance in field-annealed Co 70 Fe 5 Si 15 Nb 2.2 Cu 0.8 B 7 amorphous ribbon J. Appl. Phys. 97, 10M108 (2005); 10.1063/1.1854891 Giant magnetoimpedance of amorphous ribbon/Cu/amorphous ribbon trilayer microstructures

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The effects of composition and additives on the microstructures and magnetic properties of Nd-Fe-B melt-spun ribbons were studied. Experimental results have revealed that homogeneous grain structure with fine grain size was obtained on composition close to 2-14-1 stoichiometry with additives. It was also found that Nb was very effective in increasing both remanence and coercivity in a Nd-Fe-B melt-spun ribbon. A high-energy product of 151.2 kJ/m3 (19.0 MGOe) was obtained from an isotropic (Nd0.5Pr0.5)12Fe72Co8B6Nb2 melt-spun ribbon with a remanence of 0.926 T and a coercivity exceeding 1200 kA/m (∼15 kOe).

The phase transformation of NdFeB melt-spun alloys with low Nd content of 4–8 at. % was investigated by thermomagnetic analysis and x-ray diffractometry. Experimental results have shown that the metastable Nd2Fe23B3 compound formed in the alloys is considered to be transformed to Nd2Fe23B3+α-Fe+Fe3B in the temperature range of 550–690 °C, α-Fe+Fe3B+Nd1+eFe4B4 in the temperature range of 690–730 °C and finally α-Fe+Nd1+eFe4B4 above 840 °C. From the results, it has been concluded that Nd2Fe14B is not formed from metastable Nd2Fe23B3. On the other hand, the melt-spun alloy of Nd2Fe23B3 (∼Nd7.1Fe82.1B10.7) annealed under optimum conditions has been found to be composed of α-Fe, Fe3B, and Nd2Fe14B phases. The alloy has a coercivity comparable to Fe3B-based Nd4Fe77B19 and relatively high-energy product of about 71.6 kJ/m3 (∼9 MG Oe).