Preparation and magnetic properties of co-based bulk glassy alloys

This paper deals with the formation and soft magnetic properties of Co(Fe)-M-B (M = transition Metals) glassy alloys in thin sheet and bulk ring forms prepared by single role melt spinning and copper mold casting methods. This multicomponent system was found to exhibit a distinct glass transition and a wide supercooled liquid region (DeltaT(x)) exceeding 70 K before crystallization. The high thermal stability of the supercooled liquid has enabled us to produce the bulk glassy alloys. The Co-Fe-Ta-B alloy samples with a ring form of phi7 mm x phi3 mm, x t1 mm consist of a single glassy phase. These bulk amorphous samples exhibit excellent soft magnetic properties, which are nearly the same as those of the corresponding melt-spun glassy thin sheets: the coercivity (H-c) and saturation magnetic flux density (B-s) are 0.25 A/m and 0.49 T, respectively. These good soft magnetic properties suggest structural homogeneity resulting from its high glass-forming ability. The excellent soft magnetic properties are useful for industrial application.