Characterization of phase constitution and magnetic properties of the hard magnetic nanocrystalline Nd9.5Fe63.65B21.85Nb5 alloy ribbons

In order to investigate the phase constitution of the nanocrystalline Nd9.5Fe63.65B21.85Nb5 alloy ribbons in the as-cast state and after short-time annealing Mossbauer study has been carried out. In as-cast state, ribbon samples were not fully amorphous but revealed soft magnetic properties. X-ray diffraction analysis showed the presence of hard magnetic Nd2Fe14B, metastable Nd2Fe23B3 and paramagnetic Nd1+epsilonFe4B4 phases in annealed samples. Mossbauer spectroscopy was used to determine the fractions of constituent phases formed during annealing of ribbons. Magnetic measurements were made with a vibrating sample magnetometer (VSM) and have shown that with increasing annealing temperature the remanence polarization Jr and maximum energy product (BH)max values were increasing.