Massive carburization could occur in metallic service components due to operating conditions. The changes in the microstructure resulted in severe embrittlement of the material leading to a loss of corrosion resistance. A first step in the study of the electronic structure and bonding that occurred during carburization phenomena was performed here. The interaction between a carbon atom and a Fe50Ni50 alloy containing a vacancy was studied by ASED-MO cluster calculations, firstly in a vacancy region and then on the FeNi(111) surface. The minimum energy position for the C atom in the vacancy region was found to be at 1.19Å from the vacancy centre. The addition of a C atom in the FeNi matrix containing a vacancy decreased the strength of the local Fe–Fe bond to about 80% of its original bulk value. This bond weakening was mainly a consequence of the C–Fe interaction. On the other hand, the minimum energy position of the C atom on the FeNi(111) was found to be at 1.60Å from the surface. The principal interaction was again C–Fe. The C-surface bonding was achieved mainly at the expense of the weakening of the Fe–Ni nearest neighbours bond to C, which decreased to about 52%.

A Computational Study of the Carburization Phenomena in a Fe–Ni Alloy. S.Simonetti, L.Moro, G.Brizuela, A.Juan: Journal of Physics D, 2008, 41[12], 125006 (7pp)