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Effects of heat treatment on nanocrystalline formations in Fe 40 Ni 40 (Si + B) 19 Mo 1–2 amorphous ribbon
Author(s) -
Saiseng S.,
Winotai P.,
Limsuwan P.
Publication year - 2005
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200406877
Subject(s) - nanocrystalline material , materials science , amorphous solid , differential scanning calorimetry , crystallite , ribbon , analytical chemistry (journal) , mössbauer spectroscopy , ferromagnetism , crystallization , hyperfine structure , magnetization , phase (matter) , quadrupole splitting , crystallography , mössbauer effect , metallurgy , condensed matter physics , magnetic field , nanotechnology , chemistry , thermodynamics , composite material , physics , organic chemistry , chromatography , quantum mechanics
Effects of heat treatment on Fe 40 Ni 40 (Si+ B) 19 Mo 1–2 were monitored by Mössbauer spectroscopy (MR), X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). Mössbauer spectra were fitted by using the PC‐MOS II program to obtain such parameters as hyperfine field, isomer shift and quadrupole splitting of samples annealed for two hours in argon at different temperatures. The change in direction of local magnetization and the transformation of amorphous to crystalline phase were observed. Heat treatments near the crystallization temperature between 450–500 °C resulted in nanograins of α‐Fe, α‐Fe(Si) and t‐Fe 2 B embedded in the remaining uncrystallized amorphous matrix. DSC data showed that the ribbon exhibited two‐step crystallizations at 454 °C and 525 °C, respectively. The first crystalliza‐ tion corresponded mainly to soft ferromagnetic α‐Fe, α‐Fe(Si) and some minor t‐Fe 2 B phase forma‐ tions, while the second, corresponded to t‐Fe 3 B phase. Further heat treatment at 600 °C led to complete crystallizations at which the ferromagnetic phases α‐Fe and α‐Fe(Si) transformed to a paramagnetic phase fcc‐FeNi, and ferromagnetic phases of c‐FeNi 3 , t‐Fe 2 B, t‐Fe 3 B, and Ni 2 Si, respectively. Due to the high mag‐netic anisotropy of t‐Fe 2 B and other phases as well as to keep the crystallites in the nano region, the Fe 40 Ni 40 (Si‐B) 19 Mo 1–2 ribbon should not be heated above 500 °C for the superior magnetic properties. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)