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The effect of annealing and chemical composition of cold-rolled palladium–copper (57 at % Cu) and palladium–ruthenium (6 at % Ru) alloys on the processes of injection and extraction of atomic hydrogen in an aqueous solution of 0.1 M H2SO4 was studied by two-stage cathode–anode chronoamperometry. The close values of the parameters of hydrogen permeability, found from the cathode and anode chronoamperograms, indicate a low level of imperfection of the alloy structure. It has been established that the choice of a mathematical model for processing the chronoamperometry results is determined by the thickness of the alloy samples. The finite-thickness model can be applied if the sample thickness does not exceed 10 µm. Preliminary annealing of samples leads to a decrease in hydrogen permeability and an increase in the effective rate constants of the injection and extraction of atomic hydrogen. At the same time, the palladium-ruthenium alloy is characterized by a higher rate of diffusion mass transfer, while the copper–palladium alloy is characterized by increased values of the kinetic parameters of atomic hydrogen transfer. [ABSTRACT FROM AUTHOR]

The purpose of this work was to reveal the infl uence of the phase composition and the crystallographic orientation of fi lm samples of Pd-Cu solid solution on the parameters of extraction and injection of atomic hydrogen in aqueous solution of sulphuric acid. The study was carried out using a two-step cathode-anode chronoamperometry method. The fi lms of the Pd53Cu alloy of various thickness were obtained by magnetron sputtering. They were characterised by the same phase (100% of theβ -phase of a solid solution) and chemical composition. It was confi rmed that during the initial period (≤ 4 s, the injection of atomic hydrogen proceeds in a mixed diffusion-phase-boundary regime, which later transforms into a purely diffusion mode. The kinetic and diffusion parameters of the stages of phase-boundary penetration of hydrogen and its subsequent solid-phase diffusion were calculated by the cathodic and anodic current decays. It was established that regardless of the thickness of the sample, an increase in the β phase fraction in the alloy leads to a marked increase in the diffusion coeffi cient of atomic hydrogen and, consequently, to an increase in the hydrogen permeability constant. The crystallographic orientation only affects the stage of phase-boundary penetration of hydrogen into the fi lm alloy. The data obtained confi rm the preferential movement of hydrogen along the grain body rather than over the interphase boundaries.