Stress relief by annealing under external stress in Fe-based metallic glasses

The effects of stress relief on the magnetic characteristics of Fe-based metallic glass (MG) ribbons are investigated under external stress through various annealing treatments. We found that long-time annealing treatments benefit for making softer magnetic MGs under applied bending stress. We show that the irreversible domain wall movement region and the irreversible domain wall rotation region in the M-H curve represent the stress relief, which can be well reflected by the demagnified magnetic anisotropy. The magnetic coercivity and effective permeability variations in the lower frequency regime also represent the stress relief state. These observations have implications for understanding the relationship between the stress relief, microstructure change, and magnetic softness in magnetic MGs and might be helpful for the performance improvement of the ferromagnetic glassy materials.