computational study of the hydrogen embrittlement phenomena in an iron nickel based alloy

S. SIMONETTI, G. BRIZUELA, A. JUAN

Lisboa

Simposio; HYPOTHESIS VIII, Hydrogen – Power Theoretical and Engineering Solutions; 2009

International Hydrogen Energy Association

The interaction between an H atom and a Fe50Ni50 alloy containing a vacancy was studied. The energy of the system was calculated by the Atom Superposition and Electron Delocalization Molecular Orbital (ASED-MO) method. The electronic structure was studied using the concept of density of states (DOS) and crystal orbital overlap population (COOP) curves.  The minimum energy position for the H atom in the vacancy region was found at 1.32 Å from the vacancy center. The changes in the electronic structure of Fe and Ni atoms near the vacancy were analyzed. The interactions mainly involve Fe and Ni metal 4s and 4p atomic orbitals. The contribution of Fe orbitals is the most important. The Fe-Fe, Fe-Ni and Ni-Ni bonds weakened as new Fe-H was formed. The effect of H atoms is limited to its first neighbors. The detrimental effect of H atoms on the metallic bonds can be related to the mechanism for H embrittlement.