2002 Volume 43 Issue 5 Pages 1230-1234
Soft ferromagnetic bulk glassy alloys in Co–Fe–Si–B base system were formed in the diameter range up to 1 mm at the composition of (Co0.705Fe0.045Si0.1B0.15)96Nb4 by copper mold casting. Since no bulk glass formation has been obtained in the Co–Fe–Si–B system, the addition of 4%Nb is very effective for the increase in the glass-forming ability. The effectiveness was interpreted by satisfaction of the three component rules for formation of bulk glassy alloys. The bulk glassy alloys exhibit the glass transition before crystallization. The glass transition temperature (Tg), the supercooled liquid region defined by the difference between Tg and crystallization temperature (Tx), ΔTx (=Tx−Tg) and the reduced glass transition temperature (Tg⁄Tl) are 823 K, 37 K and 0.61, respectively. The bulk glassy alloys also exhibit soft magnetic properties with saturation magnetization (Is) of about 0.60 T and low coercive force (Hc) below 3 A/m. The synthesis of the Co-based bulk glassy alloy rods with glass transition and good soft magnetic properties is important for future development as a new type of soft magnetic bulk material.
