Effect of yttrium substitution on magnetic properties and microstructure of Nd-Y-Fe-B nanocomposite magnets

The phase evolution, microstructure and magnetic properties of Nd9–xYxFe72Ti2Zr2B15 (x=0, 0.5, 1, 2) nanocomposite ribbons were investigated. It was found that substitution of Y enhanced glass forming ability of the over-quenched ribbons and stabilized the amorphous phase during post annealing treatment. Appropriate content of Y substitution effectively refined the microstructure and enhanced the remanence of the annealed samples. The residual amorphous intergranular phase in the annealed sample improved the squareness of loops, resulting in enhanced maximum energy product. The optimum annealing treatment significantly improved magnetic properties of the Y substituted ribbons. Best magnetic properties, Jr=0.78 T, Hci=923.4 kA/m, (BH)max=98.5 kJ/m3 were obtained from Nd8YFe72Ti2Zr2B15 ribbon spun at Vs = 4 m/s, and annealed at 700 °C for 10 min.