Magnetic properties of Nd-rich RECo5-magnets

The hard magnetic properties of RE1-xNdxCo5magnets with RE = MM and Sm have been studied as a function of the Nd-coneentration up to 65 at% Nd of the RE fraction. ´In MM-based magnets of the composition (MM0.85Sm0.15)Co5a maximum of the eoereivity was found for Nd-concentrations between 20 and 30 at% of the rare earths fraction. The magnetic remanence increases steadily with the Nd-concentration in the whole range of composition studied, from 8 KG for 0 at% up to 9.2 KG for 65 at%. A similar behaviour is found for Sm-based magnets. We have also studied the temperature dependence of both coereivity and magnetic remanence as a function of the Nd content. The coereivity-temperature curves of the magnets show a maximum, the position of which depends on the Nd-concentration. With increasing Nd-concentration the maximum is shifted to higher temperatures. This is related to the temperature dependence of the anisotropy field of these alloys which is strongly influenced by Nd-concentration. We also measured the dependence of the coercivity on the angle between the direction of easy magnetization and the applied fields. These measurements are compared with measurements of the primary magnetic properties of (MM1-xNdx)Co5as well as Sm1-xNdxCo5single crystals.