Magnetic properties, phase evolution, and structure of melt spun SmCo_(7-x)Nb_x (x= 0-0.6) ribbons

摘要

The phase evolution, microstructure, and magnetic properties of melt spun SmCo_(7-x)Nb_x (x =0-0.6) ribbons have been investigated using powder x-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer, respectively. SmCo_(7-x)Nb_x ribbons could crystallize in TbCu_7-type structure only for low Nb substitution of x=0-0.3 at high wheel speed of 30-40 m/s. According to the structure refinement, the doping element Nb prefers to occupy the 2e site. The intrinsic coercivity increases dramatically from 1.9 kOe for SmCo_7 ribbon to 10.2 kOe for SmCo_(6.8)Nb_(0.2) ribbon at wheel speed of 40 m/s. The mechanism of the coercivity enhancement has been discussed. The optimal magnetic properties of σ_r=54.4 emu/g and _iH_c=10.2 kOe were obtained in SmCo_(6.8)Nb_(0.2) ribbon.