Annotation of the results obtained in 2023
Samples of thin foil for research were obtained in the process of multistage rolling of an ingot of the appropriate composition. The initial billets in the form of an ingot were obtained by melting the charge in an electric arc furnace with a non-consumable tungsten electrode on a copper water-cooled hearth in an atmosphere of purified helium at a small overpressure. Then, on a specially made hearth, using the same technology, a flat blank was melted from the initial ingots for conversion into foil. The shrink shell at the end of the workpiece was cut off. To homogenize the solid solution, the ingot was annealed for 5 hours in a vacuum of 6 × 10^-3 Pa at a temperature of 1000 ° C. The primary deformation of the ingot was carried out without heating on a two-roll rolling mill with compression of 18-20% per pass. When the total degree of compression was reached 70-80% (to a thickness of about 2 mm), the workpiece was annealed at 850 ° C for 5 hours. Subsequent rolling of the strip from a thickness of 2 mm was carried out sequentially to a thickness of 300±20, 200±20, 150±30, 100±20 microns on a four-roll mill (QUARTO 110/320x300) at room temperature. When the total compression ratio of 50-55% was reached, the strip was annealed at 900-950 ° C for 3 hours. The final stage of cold rolling up to 20 ± 10 microns was carried out on a twenty-roll mill (using rolls with a diameter of 8 mm). After rolling at all stages and after heat treatment cycles (HT), the foil was examined by X-ray diffractometry on an ARL-XTRA diffractometer. The orientation ratios between α and β phases and the dispersion of the substructure were determined from electron diffraction patterns and interference contrast within the areas of overlap of α and β phases of thin cross sections of foil (transmission electron microscope (TEM) - Carl Zeiss Libra-120). The elemental composition of the initial alloy was determined by energy dispersion analysis using a scanning electron microscope (JSM-6510LV) and an Auger electron spectrometer (DESA-100 analyzer). The most common patterns for the initial (after deformation) samples are as follows: a two-phase structure with a greater proportion of the β-phase, which confirms the position that a large deformation contributes to the α→β transformation. The elemental composition of the surface of the foil samples after rolling does not depend on the composition of the ingot of the initial blank. The catalytic activity of the foil surface was evaluated by cyclic voltammetry. The measurements were carried out using an electrode made of spectrally pure graphite. Metal samples were applied to this electrode using conductive graphite glue (spectral graphite powder placed in a solution of polystyrene foam in toluene). It was found that the surface of the foil after rolling is insensitive to potential cycling, as evidenced by the absence of a local maximum in the potential range of 0.3-0.5 V, characterizing the ionization process of atomic hydrogen The processes of ordering and disordering were studied in situ by X-ray diffractometry on an ARL X'TRA diffractometer (Thermo Fisher Scientific, USA) and resistometry in heating-cooling cycles. The mutual orientation and substructure of adjacent phases α and β were studied by methods of electron diffraction TEM, and energy dispersive X-ray microanalysis (ERMA) on a transmission/scanning electron microscope (TEM/SEM) Osiris (Thermo Fisher Scientific, USA) at an accelerating voltage of 200 kV. The device is equipped with a high-angle ring dark-field detector (Fischione, USA) and an energy dispersive X-ray spectrometer Super X (ChemiSTEM, Bruker, USA). Image processing was performed using Digital Micrograph software (Gatan, USA) and TIA (Thermo Fisher Scientific, USA). The samples for electron microscopy and microanalysis studies were prepared by the Ga+ focused ion beam method in a two-beam scanning electron ion microscope Helios Nano Lab 600i (Thermo Fisher Scientific, USA) at an accelerating voltage of 30 kV at the initial stages and 2 kV at the final stages. It has been experimentally established that in solid solutions of the Cu-Pd system, of a composition extremely close to the equiatomic one, spatial stratification occurs with accommodation of regions of different elemental composition that are accommodated by means of elastic deformation. According to the provision on the need to deviate from the equiatomic composition towards the copper content in order to increase the probability of the formation of the β-phase, stratification reduces the rate of α ↔ β transformations. The effect of the resulting heterostructure can be used: to substantiate hydrogen permeability, taking into account molecular modeling data, mechanical properties of the membrane foil; concentration dependence of electrical resistance of non-ordered solid solutions of binary systems. The following scientific results have been obtained. Samples of Pd-Cu alloy foil were made in the concentration range of 36 at.%Pd and composition close to the equiatomic (the rest is Cu), their certification was carried out in terms of phase composition, elemental composition of the surface and catalytic activity. The narrowing of the distribution of relief heights indicates the removal of some of the artifacts of the rolling process from the foil surface without changing its substructure. The elemental composition of the membrane foil surface corresponding to the composition of the initial alloy is achieved by cleaning it for 240 minutes, including rinsing in an ultrasonic bath with acetone followed by rinsing in distilled water. It has been established that the slowing down of the hydrogen sorption process at the initial stage of cycling occurs due to the adsorption of gas molecules from the medium after cleaning the foil surface. With an increase in the duration of ultrasonic treatment, the sorption coefficient and the rate constants of injection and extraction of atomic hydrogen increase. The preservation of hydrogen permeability after ultrasonic treatment indicates that the determining factor is the activation energy of hydrogen diffusion in the sample volume. As a result of ion-beam irradiation, the surface is completely freed from rolling artifacts, the development of relief, the formation of microcracks and, accordingly, an increase in the effective surface area. Photonic processing of a foil with a composition close to the equiatomic one does not contribute to the formation of an ordered structure. The value of hydrogen permeability in the temperature range of 100-400 °C for single-phase (β-phase) foil in the concentration range of 40-46 at.% Pd ranges from 4.31 to 4.72•10^-4 m•^s-1•MPa^-0.5; for single-phase (β-phase) foil in the concentration range of 45-52 at.% Pd – from 2.62 to 2.70•10-4 m•s ^-1•MPa^-0.5. The hydrogen permeability of the Pd-Cu foil system is limited by the inclusion of structural units of the BCC with an excessive content of Cu atoms and stratification by elemental composition when it approaches the equiatomic.

 

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