The effect of V and C contents on the magnetic properties and phase evolution of melt-spun SmCo7-xVxCy (x=0-0.6; y=0-0.1) ribbons

The effect of V and C contents on the magnetic properties and phase evolution of melt-spun SmCo7-xVxCy ribbons has been investigated. For SmCo7-xVx ribbons spun at a high wheel speed of 40 m s-1, only a pure TbCu7-type structure is found for low V substitution of x=0-0.3, but the secondary phase Sm2Co17 appears when x is higher than 0.3. Besides, the cooling rate is the crucial factor to stabilize the TbCu7-type phase and to modify the microstructure of the ribbons. In SmCo7-xVx series ribbons, the magnetic properties of σr=55.3 emu g-1, iHc=9.2 kOe and (BH)max=8.0 MGOe were obtained for SmCo6.8V0.2 spun at the high wheel speed of 40 m s-1. Furthermore, a slight C addition effectively refines the grain size, and leads to the rapid improvement of magnetic properties. The optimal magnetic properties of σr=58.7 emu g-1, iHc=13.5 kOe and (BH)max=9.3 MGOe could be obtained for SmCo6.9V0.1C0.1 spun at 40 m s-1.