Texture of Nanocomposite Nd2Fe14B／α-Fe Melt Spun Ribbons

Highly textured nanocomposite Nd9Fe84.5Nb0.5B6 ribbons were obtained by rapid solidification at wheel speeds from 15 to 20 m·s^-1. X-ray diffraction (XRD) shows that these ribbons are preferentially orientated with the c axis of Nd2Fe14B phase perpendicular to the surface of the ribbons. The texture of Nd2Fe14B phase on the free surface is stronger than that on the contact surface and decreases with increase of wheel speed. The texture of Nd2Fe14B phase seems to be caused by the preferential growth of the crystal nuclei favorable orientation with their c-axes along the temperature gradient during rapid solidification, which can be explained by a growth circular cone (GCC). The intensity of the anisotropy can be expressed by the magnitude of the cone generating angle. The supercooling velocity and wheel speed will influence the cone generating angle, which in turn influences the anisotropy. The remanence and maximum energy product in the direction perpendicular to the ribbon surface is much higher than that in the direction parallel with the ribbon surface. High remanence and maximum energy product can be obtained in the direction perpendicular to the ribbon surface. The texture of Nd2Fe14B phase decreases gradually after annealing above 600°C, which is mainly attributed to the precipitation of new α-Fe from Nd2Fe14B phase with super-saturated Fe. Decreasing the annealing temperature or reducing the annealing time is beneficial for preserving the anisotropy of Nd2Fe14B phase after annealing.