Ductile FeNi-based bulk metallic glasses with high strength and excellent soft magnetic properties

Fe-based bulk metallic glasses (BMGs) have attracted great attention due to their excellent soft magnetic properties and high fracture strength, but few applications have been materialized as structural materials because of their brittleness at room temperature. Here, we successfully synthesized an Fe39Ni39B14.2Si2.75P2.75Nb2.3 BMG which exhibits large plastic strain of 7.8%, high fracture strength of 3.35 GPa and excellent soft magnetic properties, i.e., rather high saturation flux density of 0.88 T, low coercive force of 0.7 A/m and high permeability of 20800. The results indicated that the mutual repulsion between ductility and strength could be renovated in the Fe-based BMGs by the rearrangement of atomic configurations through Ni addition. With proper combination of non-directional metal-metal bonds and directional metal-metalloid bonds, the mechanical properties of FeNi-based BMGs can be improved. Our studies provide a guideline in designing ductile FeNi-based BMGs with high strength, large GFA and excellent soft magnetic properties.