Formation of carbide phases upon the mechanosynthesis of the (Fe0.93Cr0.07)75C25 alloy compared with other carbide-forming processes

Resumo

Methods of X-ray diffraction, differential thermal analysis, and measurements of the dynamic magnetic susceptibility have been used to investigate the sequence of phase transformations upon the mechanical alloying of a mixture of powders of the initial components of the composition (Fe_0.93Cr_.07)₇₅C₂₅. It has been shown that, at later stages of mechanical alloying, the phase composition is determined by the conditions of the dynamic equilibrium between the crystalline and amorphous phases. A change in the conditions of mechanical alloying leads to a shift in this equilibrium and to a change in the phase composition of the alloy. A comparison of carbide formation in the Fe–C system upon the mechanosynthesis, tempering of martensite, the saturation of iron with carbon from the gaseous medium, the quenching of the melt, and the sputtering deposition of films has been performed. Some general regularities have been established, from which it follows that an important role in phase formation upon the mechanosynthesis, just as in other abovementioned processes, is played by the thermally activated phenomena.