Lattice dynamics of hydrogenated austenitic steels

Abstract

We investigated hydrogen vibrations in of Fe 18Cr-10Ni and Fe-25Cr-20Ni austenitic steels doped in H gas atmosphere at pressures up to 7 GPa. Measurements were performed with neutron spectrometers FANS at NIST and TOSCA at ISIS. Experiments show that vibrational energy of H atoms in studied steels decreases from 132 meV at H/Me=0.0033 to 111 meV at H/Me=0.9 due to lattice dilatation. The hydrogen peaks are broadened. At H contents from 0.003 to 0.4-where the single broad peak is observed-the broadening is most probably connected with the Me-H force constant disorder. At H/Me>0.4-0.5-where H-peak has the two-component structure-the H-H interaction becomes important resulting in the dispersion of the optical phonon branches.