Structure and hard magnetic properties of rapidly quenched Sm-Co-B alloy ribbons

The hard magnetic properties of the Sm-Co-B ternary alloy ribbons in the composition range, 9<Sm(at%)<16,2<B(at%)<5,bal.Co, were systematically examined. The dependences ofiHcand (BH)maxon the fabrication conditions and also the concentration were clarified. The maximum value of (BH)maxfor the ternary alloys, 8MGOe, was obtained for the ribbons with the concentration, about 12 at%Sm, 4at%B.bal.Co. Addition of B to the Sm-Co binary alloy ribbons was found to be effective to the increase ofiHcin the Sm concentration range between 9 and 12at%. The structural analysis revealed that the ribbons whose hard magnetic properties were improved by the addition of B consist of two phases,namely Sm2Co14B phase and the high temperature phase of Sm2Co17. The ribbons which show the maximum value of (BH)maxconsists of fine spherical grain particles ( m in diameter). The influences of the addition of B on the hard magnetic properties and also on the structure are discussed.