Cobalt-based bulk glassy alloy with ultrahigh strength and soft magnetic properties

Bulk metallic glasses-formed by supercooling the liquid state of certain metallic alloys-have potentially superior mechanical properties to crystalline materials. Here, we report a Co43Fe20Ta5.5B31.5 glassy alloy exhibiting ultrahigh fracture strength of 5,185 MPa, high Young's modulus of 268 GPa, high specific strength of 6.0x10(5) Nm kg(-1) and high specific Young's modulus of 31x10(6) Nm kg(-1). The strength, specific strength and specific Young's modulus are higher than previous values reported for any bulk crystalline or glassy alloys(1-3). Excellent formability is manifested by large tensile elongation of 1,400% and large reduction ratio in thickness above 90% in the supercooled liquid region. The ultrahigh-strength alloy also exhibited soft magnetic properties with extremely high permeability of 550,000. This alloy is promising as a new ultrahigh-strength material with good deformability and soft magnetic properties.