INFLUENCE OF MO ADDITION ON THE MICROSTRUCTURE AND MAGNETIC-PROPERTIES OF SM-2(FE, AL, MO)(17)C-1.5 ALLOYS

The microstructure and magnetic properties of Sm2Fe(15.5-x)MoxAl1.5C1. 5 alloys with Mo additions have been investigated by means of XRD, SEM , TEM, and magnetic measurements. The as-cast alloys have a multiphase structure consisting of a 2/17-type carbide, a considerable amount of alpha-Fe, and a SmFe2 phase. Through rapid quenching, the SmFe2 phase is removed and the amount of alpha-Fe greatly reduced in the quenched ribbons. It is found that the addition of Mo can produce fine grains and simultaneously decrease the amorphous tendency of the ribbons. The magnetic hardening of Mo-containing alloys can be achieved by direct quenching. With increasing Mo content within a wide range, the coerciv ity of the ribbon gradually increases while its remanence remains appr oximately constant. An optimal coercivity exceeding 1.35 T is obtained for the Sm2Fe14.9Mo0.06Al1.5C1.5 ribbon spun at 40 ms(-1). The reduce d remanence of the ribbon is beyond 0.7. These results reveal that the addition of Mo is very effective on improving the coercivity and enha ncing the exchange coupling between the 2/17-type and alpha-Fe phases. (C) 1998 Elsevier Science B.V. All rights reserved.