Experimental and Theoretical Studies of Thermal Desorption Spectra of Hydrogen Dissolved in Amorphous Alloys

Abstract

Thermal desorption spectra (TDS) of hydrogen dissolved in amorphous Fe-Ti and Ni-Zr alloys have been measured. Each spectrum presents, below the crystallizing temperature TX, a broad maximum which continually shifts toward lower temperatures with increasing initial hydrogen concentrations. This maximum usually consists of a few peak components which originate from the desorption of hydrogen atoms occupying nonequivalent sites in the amorphous alloy. An atempt was made to simulate the TDS spectra by employing a surface recombination model in which the desorption rate is controlled by the reaction H+H→H2 at the surface. Assuming that the site energy distribution function, N(E), for the dissolved H atoms is given by a combination of a few Gaussians, the TDS has been calculated and compared with the observed spectrum. With a proper choice of the Gaussian parameters, a good fit was obtained between the simulation and the experiment. The physical meaning of N(E) involving the plural Gaussian distributions is discussed.