The electronic effect of carbon and hydrogen in an ( 111 ) edge dislocation core system in bcc iron

S. SIMONETTI; E. PRONSATO; G. BRIZUELA; A. JUAN

Applied Surface Science

Año: 2003 vol. 217 p. 56 - 67

The Fe-C-H interaction in a dislocated bcc structure was studied using qualitative structure calculations in the framework of the atom superposition and electron delocalisation molecular orbital (ASED-MO) theory. Calculations were perfomed using Fe85 cluster to simulate a dislocated bcc structure. The cluster geometry and atomic parameters were optimized to make a better approximation to the repulsive  energy terms. The most stable position for C atom inside the cluster was determined. Therefore, and H atom was approximated to the minimum energy region where the C atom was previously located. The total  energy of the cluster decreases with the C atom near the dislocation core. The a/2 [111] dislocation creates an energetically favourable zone for accumulation of C. The presence of C in the dislocation core make no favourable H accumulation. The C acts such as expeler of H and could reduce the hydrogen atom weakening the Fe-Fe bons.