Iron carbide, FeC

Tze Tzeli, D., Mavridis, A. Theoretical investigation of iron carbide, FeC, J. Chem. Phys. 116 (2002) 4901-4921. 

By now, it is clear that superplasticity is not restricted to a special group of materials. Even other carbides than the aforementioned SiC show superplasticity under certain conditions. Iron carbide, FeC, is such a carbide. 

FeCs, also known as cohenite, particularly when found mixed with nickel and cobalt carbides in meteorites (Hutchison 2007), was first identified by Ernst Wein-schenk, a German pioneer of microscopy and petrography in Munich. A general formula of cohenite is (FeNiCo)3C suggesting that this mineral also comprises the earth s core. In molten iron (above 1100°C) carbon can be dissolved up to 4.3%, about double the carbon content in cohenite (2.2%). The carbon solubility increases with temperature and when the solution slowly cools down, carbon in excess of 4.3 % separates as graphite. We have no information on carbon in the earth s core but we can speculate on it and assume that some was also mixed within other upper layers. A carbon content of 1.4-2.3 % has been found in native iron (Clarke 1920). 

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