Initial stage of mechanical alloying in the Fe-C system

Mossbauer spectroscopy (MS), X-ray diffraction, transmission electron microscopy (TEM), Auger spectroscopy, magnetic measurements and differential thermal analysis (DTA) were used to study the initial stages of mechanical alloying in the Fe-C system. The mechanical alloying of Fe and C powder mixtures with the atomic ratio 85:15 in a planetary ball mill was taken as an example. It has been shown that the initial stage involves the formation of nanostructure in the alpha-Fe particles, penetration and segregation of carbon along the alpha-Fe grain boundaries, formation of the amorphous Fe-C phase in the interface regions consisting of the boundary and close-to-boundary distorted zone. The carbon concentration in the amorphous Fe-C phase is estimated at 25 at.%. The amount of the amorphous phase reaches 67 at.% (67% of all the Fe and C atoms are in this phase). (C) 2003 Elsevier B.V. All rights reserved.