Based on the ab initio calculations of the electron structure, it was shown that N and H in the Fe increase the state density at the Fermi level, whereas C decreased it, which was consistent with the available experimental data of conduction electron spin resonance. The results of calculations and measurements of the strain dependent internal friction and Snoek–Köster relaxation were used for the analysis of the interaction between dislocations and mobile or immobile interstitial atoms. It was shown that, if the moving dislocations in the Fe-based austenite and ferrite were accompanied by the clouds of interstitial atoms, nitrogen and H increase the velocity of dislocations, whereas C decreased it. The obtained results were interpreted in terms of the local change in the density of free electrons within the dislocation atmospheres resulting in the corresponding change in the line tension of dislocations. Possible consequences for mechanical properties were discussed using the examples of H embrittlement and nitrogen-caused quasi-cleavage of austenitic steels.

Change in the Electron Structure Caused by C, N and H Atoms in Iron and its Effect on their Interaction with Dislocations. V.G.Gavriljuk, V.N.Shivanyuk, B.D.Shanina: Acta Materialia, 2005, 53[19], 5017-24