Hard magnetic properties and microstructures of melt-spun SmCo5Fex (x=0, 1and 2) ribbons

Three Fe-rich SmCo5Fex (x = 0, 1 and 2) ribbons were prepared directly by m elt spinning using a wheel speed of 25 m s(-1). The x = 2 ribbons possessed the best hard-magnetic properties, intrinsic coericivity 8.2 kOe, saturati on magnetization 117.72 emu g(-1), and maximum energy product 16.06 MGOe. T he microstructures were investigated by transmission electron microscopy. T he x = 0 ribbons showed striated grains with varied compositions, such as S mCo5, SmCo3, Sm54Co46, etc. In contrast, the x = 1 and 2 ribbons showed cel lular microstructures. However, the boundary phases were found to be differ ent, Sm(Co,Fe), for the x = 1 ribbons and both Sm(Co,Fe)(3) and Sm-2(Co,Fe) (7) for the x = 2 ribbons. The correlation between magnetic properties and microstructures is discussed in detail. The coercivity mechanism is explain ed according to the temperature dependence of coercivity by the nucleation model. In turn, the dependence of the small microstructure parameters alpha (k) and N-eff on intergrain exchange coupling were analysed in nanoscale gr ains of SmCo5Fe2 ribbons.