The effect of the Mo addition on the magnetic properties and phase constituents of the Ce-(FeCo)–B ribbons

The effect of molybdenum (Mo) addition on the magnetic properties and phase constituents of Ce14Fe78-xMoxCo2B6 (x = 0–1.25 at %) ribbons has been investigated. The investigated ribbons have been prepared by melt spinning technique at different velocities. Samples were studied in as-cast state and after annealing. The results reveal that the addition of Mo in Ce14Fe78-xMoxCo2B6 ribbons and the subsequent annealing improves the magnetic properties. Mo acts as inhibitor of the growth of crystalline grains and reduces the volume fraction of the undesirable non-magnetic phases. As a result, the coercivity of Ce14Fe78-xMoxCo2B6 ribbons increases with the increase of Mo content from x = 0 to x = 1.25 at%, while the remanence remains unchanged up to 0.75 at% Mo content and after this value slightly decreases. Analysis of the δM curves showed that a suitable content of Mo improves the exchange coupling interaction. The optimum magnetic properties, i.e. coercivity, Hc = 6.1 kOe, remanence (Br) = 5.2 kG and energy density (BH)max = 4.92 MGOe, were obtained in ribbons with 1.0 at% Mo. The addition of Mo lead to an improvement of the magnetic properties of CeFeB-based ribbons making them good candidate precursors for the preparation of permanent magnets without heavy critical rare earths.