Soft magnetic Fe₂₅Co₂₅Ni₂₅(B, Si)₂₅ high entropy bulk metallic glasses

New Fe₂₅Co₂₅Ni₂₅(B, Si)₂₅ high entropy bulk metallic glasses (HE-BMGs) with superior soft magnetic and mechanical properties are developed. The HE-BMGs show high glass transition temperature and wide supercooled liquid region (ΔT_x). Fully glassy rods with diameters up to 1.5 mm were fabricated for the Fe₂₅Co₂₅Ni₂₅(B_0.7Si_0.3)₂₅ alloy by copper mold casting method. The HE-BMGs exhibit high yield strength of ∼3624 MPa with large plastic strain of ∼3.1%, which is superior to the pre-developed HE-BMGs. The alloys also possess good soft magnetic properties, i.e., rather high saturation magnetization of ∼0.87 T, low coercive force of ∼1.1 A/m, and high effective permeability at 1 kHz of ∼19,800. This combination of these excellent properties gives the new HE-BMGs good promise for both scientific and engineering applications.