Effect of quenching rate on the structural and hard magnetic properties of Nd-Fe-B melt-spun ribbons

The phase structure, microstructure, magnetic and thermomagnetic properties of nanostructured Nd-Fe-B melt-spun ribbons were investigated. The melt-spun ribbons have been prepared at different wheel speeds varying from 17 to 25 m/s. The hard magnetic Nd2Fe14B phase with (00l) texture, indicating preferred crystallographic orientation, was observed in all the ribbons with some alpha-Fe(Co) as the minor phase. Nd2Fe14B grains are uniformly distributed with grain sizes ranging from 50 to 150 nm. A decrease in the average grain size of Nd2Fe14B and fading away of texture formation in the ribbons were found with the increase in the wheel speeds. The best combination of magnetic properties with a coercivity of 14.5 kOe, the saturation magnetization of 132 emu/g, and the energy product of 16 MGOe was achieved at 23 m/s and these ribbons are suitable for the fabrication of hot deformation Nd-Fe-B magnets.