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

Abstract

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 of <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> and (BH) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> on the fabrication conditions and also the concentration were clarified. The maximum value of (BH) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> for 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 of <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> in 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 Sm <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Co <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</inf> B phase and the high temperature phase of Sm <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Co <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</inf> . The ribbons which show the maximum value of (BH) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> consists of fine spherical grain particles ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2\sim0.3\mu</tex> m in diameter). The influences of the addition of B on the hard magnetic properties and also on the structure are discussed.