Stydu On Tbcu₇-type Sm-co Matrix Ribbon Magnets

Sm-Co based intermetallic compounds with the TbCu7-type structure have attracted considerable attention due to their potential application as high-temperature permanent magnets. Pure binary SmCo₇ compound does not exist, and a third metal element must be added to stabilize the SmCo₇ phase with TbCu7-type structure.In this paper, SmCo₇, SmCo₇(CNTs)_0.05, SmCo_6.1Si_0.9, SmCo_6.1Si_0.9(CNTs)_0.05, SmCo_7-xGa_x(x=0.1, 0.5, 0.9, 1.0, 1.2), SmCo6GaC, SmCo6Ga(CNTs)_0.05 and SmCo5Cu2(CNTs)x (x=0, _0.05, 0.1) with TbCu7-type structure have been prepared by melt-spinning method. X-ray diffractometer, scanning electronic microscope, vibrating sample magnetometer and Thermal analyzer are used to analyze the influence of melt-spun speeds, doping elements, and the addition of C and CNTs on the phase structure, micro-structure and magnetic properties of melt-spun ribbons.It was found that Si, Ga and Cu were beneficial for stabilizing the metastable SmCo₇ phase and increasing the magnetic anisotropy of SmCo₇ phase. However, the addition of C and CNTs decrease the stability of the SmCo₇ phase. The rapid quenching speed is the key factor to form the TbCu7-type structure phase. The magnetically oriented SmCo_6.1Si_0.9 samples show strong magnetic anisotropy. All as-spun ribbons exhibit high magnetic properties, while the magnetic properties of as-cast alloys are lower except SmCo5Cu2(CNTs)x (x=0,_0.05,0.1) alloys. It was also found that a slight addition of C or CNTs could further refine the microstructure, resulting in improving the magnetic properties of the ribbons. Considering the magnetic properties of ribbons melt-spun at different quenching speeds, 40 m/s is the best melt-spinning speed. The optimal magnetic properties of Hc=19786Oe, M2T =88.7emu/g, Mr=70.8 emu/g and Mr/M2T=0.80 were achieved for SmCo6Ga(CNTs)_0.05 ribbons melt-spun at 40m/s. Different components of the ribbons changed the coercivity mechanisms of as-spun ribbons. Magnetization reversal mechanism of SmCo₇ and SmCo_7-xGa_x ribbons is typical nucleation mechanism, while that of SmCo₇(CNTs)_0.05, SmCo_6.1Si_0.9 and SmCo_6.1Si_0.9(CNTs)_0.05 ribbons are nucleation and pinning mechanisms coexisting, particularly, the ribbons doped with CNTs and Si show a stronger pinning mechanism.