Microstructure change in Fe-based metallic glass and nanocrystalline alloy induced by Liquid Nitrogen treatment

Abstract The effects of acyclic liquid nitrogen (LN) treatment in a temperature range of −196 °C to 50 °C on the thermal and magnetic stability of Fe78Si9B13 and Fe73.5Si13.5B9Nb3Cu1 glassy ribbons have been studied. The intrinsic heterogeneities of the metallic glasses can be activated through cryogenic thermal cycling, making irreversible structural changes after the treatment and inducing rejuvenation to the materials. The microstructural changes of both Fe-based metallic glass (MG) and nanocrystalline alloy induced by LN treatment were investigated. The experimental results show that the LN treatment could effectively rejuvenate the Fe-Si-B MGs and change their thermomechanical and magnetic properties. Based on the partially-crystallinity and well-known magnetic constants, the increase of the energy at the order of 10 mJ/g and magnetic domain wall movement and rotation at the order of 5-6 μm and 0.5°-0.8° are found for FINEMET-type amorphous alloy after LN treatment. It is also found that LN treatment can contribute a little stored energy to the magnetic domain wall movement and magnetic domain rotation.