Bulk glassy Co43Fe20Ta5.5B31.5 alloy with high glass-forming ability and good soft magnetic properties

A new Co-based bulk glassy alloy Co43Fe20Ta5.5B31.5 exhibiting a large supe rcooled liquid region before crystallization and good soft magnetic propert ies was synthesized by the copper mold casting method. The glass transition temperature (T-g) is 910 K and the supercooled liquid region (DeltaT(x)) r eaches 70 K. The high thermal stability of the supercooled liquid enabled u s to produce bulk glassy alloys with diameters up to 2 mm. These bulk glass y alloys exhibit good soft magnetic properties, i.e., saturation magnetizat ion of 0.5 T, very low coercivity of 0.9 A/m, and very high permeability of 40000 at 1 kHz. It is noticed that the diameter of 2 mm is the largest val ue for Co-based bulk glassy alloys reported up to now: The success of formi ng the large-scale size Co-based bulk glassy alloy with high thermal stabil ity of supercooled liquid and good soft magnetic properties is encouraging for future uses of bulk amorphous soft magnetic materials.