Improvement of Magnetic Property for Melt Spun CeCo₅ Ribbons Due to Fe and C-Doping

Improvement of hard magnetic property for melt spun CeCo5 ribbons by doping proper Fe and C is demonstrated. Low magnetic properties, remanence (B-r) of 4.2 kG, coercivity ((i) H-c) of 1.6 kOe, and energy product [(BH)(max)] of 1.8 MGOe, are found for binary CeCo5 ribbons due to extremely large size of grains, even prepared at a high wheel speed of 40 m/s. (i) H-c is largely enhanced to 12.8 kOe by doping C and 15.0 kOe by co-doping Fe and C, and therefore, (BH)(max) is increased to 3.5 and 5.1 MGOe, respectively. The coercivity achieved in this work is superior to those reported ever before, and (BH)(max) is also larger than the theoretical value of 4.7 MGOe for isotropic CeCo5 alloy. X-ray diffraction (XRD) and thermomagnetic analysis (TMA) results reveal Fe and C enter into the 1:5 phase to modify the lattice constant and increase T-C, and the increased c/a ratio of the 1:5 phase may improve H-a and contribute to enhancing the coercivity. Microstructure analysis indicates the grain size is effectively refined by doping C and co-doping Fe and C. Fine microstructure for C-containing ribbons contributes to attaining a high coercivity of 12.8-15.0 kOe. Besides, Fe-doping may increase the magnetization of the 1:5 phase, and therefore improve the remanence and (BH)(max). The results of this work suggest that the magnetic properties of CeCo5 ribbons could be improved by modification of 1:5 crystal and microstructure refinement due to proper Fe and C-codoping.