Hard magnetic properties of melt-spun nanocomposite Y₁₆Fe₇₈B₆ ribbons

Melt-spun Y₁₆Fe₇₈B₆ ribbons were prepared by the melt-spinning technique with pure elements Y, Fe and Fe–B alloy in argon. The ribbons are mainly composed of Y₂Fe₁₄B, YFe₂ and α-Fe phases. Amorphous phase appears at the wheel velocity of >35 m·s⁻¹. For the ribbons prepared at optimum wheel velocity and heat treatments, the coercivity, remanence and maximum energy product are 239.5 kA·m⁻¹, 0.61 T and 32.7 kJ·m⁻³, respectively. By an investigation of Henkel plots of ribbons, it is found that intergrain exchange coupling leads to the enhancement of remanence. The coercivity mechanism of ribbons prepared at 35 m·s⁻¹ is mainly controlled by inhomogeneous pinning of domain walls. The phase component and magnetic properties change with annealing temperature and time. The optimum magnetic properties are obtained with the ribbon quenched at 35 m·s⁻¹ and annealed at 700 °C for 10 min.