Influence of concentration in interstitial elements on mechanical alloying of Fe–C powder mixtures

This work concerns the mechanical alloying processing of Fe–C powders likely to be utilised for sintering of tool steel. The influence of synthesis conditions, such as milling time, gas nature in the vial (shown here as reactive) and carbon concentration in the different powder mixtures of iron and graphite, is characterised. In the second stage, the role of thermal treatment, at moderate temperature, on the highly metastable as milled products is studied. It appears that the structure is heterogeneous and shows α-ferrite, α′′′-like cubic disordered phase, hexagonal ϵ-carbonitride and θ-cementite. The presence of N₂ gas phase appears to favour a precipitation phenomenon of the Fe₃C cementite on the one hand and of epsilon carbonitride on the other hand.