详细
The effect of the action of temperature on the structure and phase composition of an
Fe3C/Fe7C3/P-phase/Cam composite obtained by mechanosynthesis of Fe–75 at % C has been studied by the methods of X-ray diffraction, Mössbauer spectroscopy, thermogravimetric analysis, and differential
scanning calorimetry. It is shown that the structural and phase changes at heating have a multistage character.
In the temperature range 315–400°C crystallization of the paramagnetic P-phase with generation of Fe3C
and/or Fe7C3 occur. In the course of heating to higher temperatures, complete decomposition of carbide
Fe7C3 (in the range 450–550°C) and partial decomposition of Fe3C (at 600°C and above) are observed. After
cooling from 800–1000°C the mechanocomposite consists of α-Fe, cementite Fe3C, and graphite. The phase
transformations are accompanied by the processes of composite oxidation with the formation of Fe3O4 oxide and its subsequent reduction. The P-phase is a disorded amorphous carbide Fe1 – xCx, which is characterized by magnetic ordering at the temperature of liquid nitrogen.