Enhancement of bending toughness for Fe-based amorphous nanocrystalline alloy with deep cryogenic-cycling treatment

The effects of deep cryogenic-cycling treatment (DCT) on the mechanical properties, soft magnetic properties, and atomic scale structure of the Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous nanocrystalline alloy were investigated. The DCT samples were obtained by subjecting the as-annealed samples to a thermal cycling process between the temperature of the supercooled liquid zone and the temperature of liquid nitrogen. Through flat plate bending testing, hardness measurements, and nanoindentation experiment, it is found that the bending toughness of the DCT samples is improved and the soft magnetic properties are also slightly enhanced. These are attributed to the rejuvenation behavior of the DCT samples, which demonstrate a higher enthalpy of relaxation. Therefore, DCT is an effective method to enhance the bending toughness of Fe-based amorphous nanocrystalline alloys without degrading the soft magnetic properties.