INVESTIGADORES
PASQUEVICH Gustavo Alberto
congresos y reuniones científicas
Título:
Application of Mössbauer thermal scans to Fe73.5Si13.5Cu1Nb3B9 amorphous alloy.
Autor/es:
P. MENDOZA ZÉLIS; F. H. SÁNCHEZ; F. A. CABRERA; G. A. PASQUEVICH; L. YING-FENG; M. VÁZQUEZ
Lugar:
San Carlos de Bariloche, Argentina
Reunión:
Workshop; Pan Amerivan Advanced Studies Institute on Physics at the Nanometer Scale; 2003
Resumen:
Melt spun Fe73.5Si13.5Cu1Nb3B9 ribbons were studied by Mössbauer thermal scans (MTS) and conventional Mössbauer spectroscopy complemented with differential scanning calorimetry. MTS was recently reported as a fully quantitative analysis tool to study single phase magnetic transitions  and reaction kinetics . In this work it was applied to study thermally induced magnetic and structural phase transitions. The scans clearly shown the magnetic phase transition of the original amorphous phase (Tc = 350 C), the nanocrystallization process, and the magnetic phase transitions of the nanocrystalline bcc-Fe(Si) phase and the remanent amorphous phase. The magnetic phase transition of the original amorphous phase is much sharper than either those of the nanocrystals or the remanent amorphous phase, suggesting a higher homogeneity (either compositional or spacial) in the first case. After the original amorphous ferromagnetic-paramagnetic transition the scan yield increases monotonously up to 530 C as a consequence of lattice softening and gradual formation of the Fe(Si) nanocrystals, then it decreases slowly because of their gradual magnetic transition either to the paramagnetic or to a superparamagnetic state. The scan after keeping the system several hours at 600 C is consistent with a fully transformed alloy, with more than 80 % of the Fe atoms in the nanocrystalline phase. The conventional Mössbauer spectra bring important complementary information useful for the understanding and analysis of the MTS.