Structural and phase transformations during heat treatment of the Fe(71.4)Si(14.3)C(14.3) amorphous alloy prepared by mechanical alloying

Differential scanning calorimetry, X-ray diffraction, Mössbauer spectroscopy of ⁵⁷Fe nuclei, magnetic measurements, and different heat treatments have been used to study the sequence and mechanisms of solid-state reactions in the Fe-Si-C amorphous alloy in the course of the structure transition to equilibrium. Three stages of structural and phase transformations have been found; these are the structural relaxation, formation of an Fe₅SiC silicocarbide, and its decomposition. It has been shown that the second and third stages occur during isochronous annealing within sufficiently narrow temperature ranges of 380–405 and 530–555°C, respectively. The kinetics of the decomposition of the metastable Fe₅SiC silicocarbide and the formation of the ordered Fe-Si alloy during isothermal annealing has been studied.