Europhys. Lett.
Volume 63, Number 1, July 2003
Page(s) 69 - 75
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 June 2003
DOI: 10.1209/epl/i2003-00479-1
Europhys. Lett., 63 (1) , pp. 69-75 (2003)

Hydrogen vibrations in austenitic fcc $\chem{Fe}$- $\chem{Cr}$- $\chem{Mn}$- $\chem{Ni}$ steels

S. A. Danilkin1, H. Fuess2, H. Wipf2, A. Ivanov3, V. G. Gavriljuk4, D. Delafosse5 and T. Magnin5

1  Hahn-Meitner-Institut - 14109 Berlin, Germany
2  Technische Universität Darmstadt - 64289 Darmstadt, Germany
3  Institut Max von Laue-Paul Langevin - 38042 Grenoble Cedex 9, France
4  Institute for Metal Physics - 252142 Kiev, Ukraine
5  Ecole Nationale Supérieure des Mines de Saint-Etienne 42023 Saint-Etienne Cedex 2, France

(Received 7 October 2002; accepted in final form 30 April 2003)

By neutron spectroscopy, we studied vibrations of $\chem{H}$ interstitials in two austenitic fcc steels ( $\chem{Fe_{0.55}Cr_{0.20}Mn_{0.10}Ni_{0.15}}$ and $\chem{Fe_{0.54}Cr_{0.27}Ni_{0.19}}$) doped with 0.37 and 0.33 at% $\chem{H}$. The band modes, in which $\chem{H}$ vibrates with its metal neighbours, cause a weak intensity in the energy range of the acoustic vibrations of the $\chem{H}$-free steels. The energies of the fundamental and the twofold local-mode excitations, in which $\chem{H}$ vibrates against its metal neighbours, were $\sim
130$ and $\sim 260$ $\un{meV}$, respectively. The respective peaks in the spectra were broadened because the metal neighbours of $\chem{H}$, and thus its vibrational energies, vary from interstitial site to interstitial site. The above energy values support an $\chem{H}$ occupation of octahedral interstitial sites.

63.20.Pw - Localized modes.
78.70.Nx - Neutron inelastic scattering.

© EDP Sciences 2003