AVS 49th International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeM

Paper VT-WeM7
Solubility and Diffusion of Hydrogen in Ordered Metals

Wednesday, November 6, 2002, 10:20 am, Room C-104

Session: Outgassing
Presenter: P. Repa, Charles University, Czech Republic
Authors: P. Repa, Charles University, Czech Republic
L. Peksa, Charles University, Czech Republic
T. Gronych, Charles University, Czech Republic
R. Ulman, Charles University, Czech Republic
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In the materials with ordered structure, such as the nanocrystalline and gradient materials, a relatively great part of the material is influenced by the interfaces between the crystals or between the components. As the interfaces differ from the bulk by the density and the topology of atoms, physical properties of the materials are influenced. As a result, the metals of that structure exhibit changes not only in ductility and other mechanical properties but also in the electric and magnetic properties as well when exposed to hydrogen. That's way knowledge of hydrogenation kinetics of the materials have become in the great interest recently. Since the measurement of the solubility and diffusion coefficient of hydrogen in the ordered metals is complicated due to mechanical properties of the measured samples, requirements on the experimental set up and measuring procedure is discussed. Results of the measurements are presented in which a sample was exposed to the hydrogen at elevated temperature in a filling chamber for a satisfactorily long time period to be saturated. Then the saturated sample was gradually heated up in a UHV system and the variations of the total pressure and partial pressures of several selected gases were registered. The total amount of gas dissolved in the sample, the values of solubility and diffusion constants could be estimated by an analysis of the obtained experimental data. A strong dependence of the solubility of hydrogen on the structure and composition of structured metals was discovered.