Carburization study in an iron-nickel alloy

S. SIMONETTI, G. BRIZUELA, A. JUAN

Rio de Janeiro

Congreso; Proceedings18th Congress IFHTSE- International Federation for Heat Treatment and Surface Engineering 18th Congress; 2010

Brazilian Metallurgical, Materials & Mining Association

Massive carburization can occur in metallic service components due to operation conditions.  The changes in the microstructure resulted in severe embrittlement of the material and leading to a loss of the corrosion resistance. In this paper, a first steep in the study of the electronic structure and bonding that occur during carburization phenomena have been performed. The interaction between a carbon atom and a Fe50Ni50 alloy containing a vacancy has been studied by ASED-MO cluster calculations, firstly at a vacancy region and then on the FeNi(111) surface. The minimum energy position for the C atom in the vacancy region was found at 1.19 Å from the vacancy center. The addition of a C atom in the FeNi matrix containing a vacancy diminishes the strength of the local Fe-Fe bond to about 80 % of its original bulk value. This bond weakening is 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 at 1.60 Å from the surface. The principal interaction is again the C-Fe.  The C-surface bonding is achieved mainly at the expense of the weakening of the Fe-Ni nearest neighbors bond to C, which decreases to about 52%.