Speaker
Description
Fe-based amorphous ribbons can acquire tailored magnetic anisotropy when crystallization occurs under applied tensile stress. However, the accompanying structural evolution and its relationship to stress-induced anisotropy are not yet fully understood. Here, the crystallization behaviour of VITROPERM 800 was investigated in real time using high-energy synchrotron X-ray diffraction. Amorphous ribbons were annealed at 510 $^\circ$C for 7200 s under tensile stresses of 0 and 1000 MPa, while two-dimensional diffraction patterns were continuously recorded. The emergence and subsequent evolution of Fe$_{3}$Si nanocrystals were evaluated through changes in diffraction-peak position and width as a function of time and azimuthal angle. Annealing without external stress produced nearly uniform lattice evolution, whereas tensile loading caused a pronounced directional dependence of the lattice strain. After two hours, the strain components reached approximately 0.923 % along the loading direction and -0.453 % in the transverse direction. The applied stress also altered the peak-width evolution and restricted crystallite growth, resulting in an average crystallite size of approximately 7.5 nm, compared with 9.6 nm in the stress-free sample. These time-resolved observations demonstrate that tensile stress modifies both the crystallization kinetics and elastic response of the emerging Fe$_{3}$Si phase. The results provide direct structural insight into the development of stress-induced anisotropy in nanocrystalline soft-magnetic alloys.
Acknowledgment
This study was funded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V03-00034. Support from the project VEGA 1/0638/24 is also acknowledged.
