Structural evolution and crystallization kinetics of Fe-based amorphous alloys under ultrasonic vibrations treatment

Abstract

Fe-based amorphous alloys are widely used in various fields such as filters, low-frequency mechanical antennas, and wastewater treatment due to their unique soft magnetic properties and band structure. Currently, several surface treatment methods, including such as high-temperature autoclave processing, high-energy particle irradiation, pulsed laser treatment, and dynamic mechanical relaxation are employed to optimize the structure and enhance the performance of Fe-based amorphous alloys. Ultrasonic vibration treatment (UVT) has gained attention for its concentrated and rapid energy application, often used as an assisted method for laser treatments. In this paper, UVT was applied directly to the amorphous alloys, with the total energy input controlled by varying the UVT time. The results of X-ray diffraction and pair distribution function from selected area electron diffraction of TEM indicate that UVT can finely tune and restore the structure of Fe-based amorphous alloys by facilitating the interconversion between bcc and fcc/rcp units according to the two-structure model. Additionally, the influence of UVT on the crystallization kinetics of the amorphous alloys was investigated by differential scanning calorimetry (DSC). The Mu-10s has the most bcc units and the highest activation energies among the samples. It was found that UVT primarily affects the crystal growth stage and does not influence the 'instantaneous nucleation - low-dimensional growth' crystallization process, which influences the soft magnetic and magnetostrictive properties of Fe-based amorphous alloys. The measured structural, thermal, and magnetic parameters of the Mu-240s show a tendency to recover toward those of the initial stage. The fine-tuning and recovery of the structure of Fe-based amorphous alloys through UVT can provide valuable control strategies for the practical applications.