Synthesis of Fe carbides species by reactive milling

The formation of iron carbides by reactive milling of alpha-Fe and C powders is reported. The products formed were analyzed by Mossbauer spectroscopy and X-ray diffraction. It was found that iron carbide phases start forming after an incubation period of about 3 h depending on the ball-to-powder weight ratio (BPR). Carbide amounts increased with increasing milling time while a-Fe content decreased. Energy transfer increased with increasing BPR and high BPR resulted in an increase in the reaction rate. Although it was not possible to selectively synthesise a specific FexC phase, samples containing predominantly one type of carbide phase, either Hagg carbide or cementite, were successfully prepared. The formation of the different iron carbide phases is discussed within the context of the Fe-C phase diagram for non-equilibrium processes.