Structural anisotropy in FeCuNbSiB alloys: An in situ synchrotron XRD study

The effect of the applied tensile stress during annealing on the structural anisotropy expressed by the shift in peak position is studied in situ using synchrotron XRD. The evolution of the diffraction spectra during in situ nanocrystallization for ribbons annealed with and without stress is also shown. There is a clear difference between the peaks in the parallel and perpendicular directions in the d-spacing between (2 0 0) planes for the stress-annealed sample while the difference is somewhat insignificant for the sample annealed without stress. The structural anisotropy for the sample annealed without stress decreases from 0.01° to 0.001° while the structural anisotropy first increased from 0.48° to 0.54° between 675 s and 828 s, decreased gradually to 0.5° after 2187 s, then decreased sharply to 0.43° as the sample is cooled to room temperature for the stress annealed sample. The (2 0 0) lattice spacing is elongated in the direction parallel to the applied stress for the stress-annealed sample. No observed elongation in the (2 0 0) lattice spacing for the sample annealed without stress. This shows that the origin of the stress-induced anisotropy is in agreement with the magnetoelastic theory.