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

•Fe–Co–Ni–B–Si high entropy bulk metallic glasses (HE-BMGs) are synthesized.•The HE-BMGs show high Tg and wide supercooled liquid region.•The HE-BMGs show good soft magnetic properties with coercive force below 2.3 A/m.•The HE-BMGs exhibit high yield strength, which are superior to the developed HE-BMGs.

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 (ΔTx). Fully glassy rods with diameters up to 1.5 mm were fabricated for the Fe25Co25Ni25(B0.7Si0.3)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.