V. V. Larionov

Properties and structural state of the surface layer in a zirconium alloy modified by a pulsed electron beam and saturated by hydrogen

A pulsed action of an electron beam on a Zr-1% Nb zirconium alloy is studied. Alloy samples are irradiated by three 50-μs pulses at an energy density of 15–25 J/cm2, a power of (3–6) × 104 W/cm2, a current density of 10–50 A/cm2, and an electron energy of 18 keV. This method of processing is found to modify the surface layer of the alloy without changing the structure-phase state of its volume. This surface modification increases the hydrogen saturation resistance of the alloy.

Ionizing radiation-stimulated diffusion and desorption of hydrogen from metals

The processes of hydrogen diffusion from a sample depth activated by electrons with an energy of tens of keV are studied. The difference from the known models of electron-stimulated desorption, which consider as a rule electron energies from 0.5 to several keV, is noted. The proposed model is shown to correspond to at least two established experimental facts: the nonlinear dependence of hydrogen isotope desorption on the electron beam current density affecting the sample and the dependence of hydrogen desorption on the irradiation time of the sample.

Radiation-Stimulated Hydrogen Transfer in Metals and Alloys

Investigations of atom and molecule emission from the surface and the surface layers of solids into vacuum under different impacts have been carried out for many decades (methods and statement of some of them are reviewed in [1–9]). But only during recent 30–40 years, due to scientific and technical achievements in obtaining and diagnostics of vacuum, it has become possible to develop methods and equipment for obtaining information on the qualitative and quantitative content of various gas impurities in compact and porous solids (e.g., hydrogen, oxygen, nitrogen, water vapor, hydrocarbon gas, CO2, CO, etc.), which are adsorbed on the surface and dissolved in the surface layer and bulk. These impurities release from heated or irradiated (by ions or electrons) materials in the form of atoms and molecules, and are detected by mass-spectrometry. In particular, it was revealed that using radiation exposure, controlling the hydrogen concentration in bulk solids, it is possible to create nonequilibrium thermodynamic systems that cannot be synthesized by traditional methods [10–12]. These problems have become urgent in recent years to researchers in different scientific areas [10, 14–16] because this allows one to achieve deep, controlled restructuring of metals and alloys on their different structure levels [10, 13]. Actively absorbing the irradiation energy, the electronic subsystem of MeHx alloys transits to excited state. Since the frequency of collective oscillations of the hydrogen subsystem is outside the phonon spectrum of the metal crystalline lattice, its relaxation is hindered. Exposed to the electron beam in the subthreshold range, hydrogen atoms begin to actively migrate through the bulk crystal and go outside. This evidences manifestation of collective properties by the internal hydrogen metal atmosphere and is represented in a number of nonlinear effects, in particular, in the dependences of the release rate, diffusion coefficients, energy of hydrogen (deuterium) atoms on the density and energy of the exciting electron beam, or X-ray quanta. It was found that the hydrogen subsystem, preserving for a long time the supplied energy on the time scale of electronic relaxation in metals, is able to stimulate processes of rapid diffusion, nonequilibrium hydrogen escape under irradiation [11, 13]. The goal of the present work: Based on investigation of hydrogen (deuterium) release from metals under ionizing radiation in the subthreshold range, to determine the optimal conditions of dehydrogenization and consider the model of hydrogen release from metals, investigate the possibility of release of nuclear reaction products, in particular, protons and alpha particles, and also to study the mechanism of energy transfer from hydrogen to nuclear subsystem. Contrary to the known models of electron-stimulated desorption (ESD) [1, 2], which normally use electron energies from 0.5 to several keV, in the present work we consider not only the processes of hydrogen molecule formation and detachment from metal surfaces, but also processes stimulating

Features of excitation of the hydrogen (deuterium)-metal system by an electron bunch

We report on the results of mass-spectroscopic analysis of the hydrogen yield from metals saturated with hydrogen under the action of accelerated electrons (with an energy of up to 100 keV and a current density from 3 to 30 μA). It is found that the desorption rate is determined not only by parameters of the electron bunch, but also by the structure of the oxide film. It is discovered that the electronic subsystem of hydrogen-enriched metals enhances their ability to absorb the energy of the external electromagnetic action and to preserve it for a longer time as compared to a pure metal. This facilitates nonequilibrium migration and yield of hydrogen under the action of radiation in the subthreshold range. A theoretical model is proposed and analytic dependences are derived for the intensity of hydrogen yield from metals exposed to an electron bunch. The results of this study can be used for the removal of hydrogen from metals and for obtaining submicrocrystalline materials (e.g., titanium).

Hydrogen diffusion in steels under electron bombardment

We report on the results of measurement of the coefficients of hydrogen diffusion through metal membranes in the course of their simultaneous hydrogen saturation and bombardment with electrons (energy 30 keV, current density from 3 to 30 µA/cm2) both in a broad and in a narrow beam. It is found that the time of hydrogen discharge from the membrane is determined by the parameters of the electron beam, its periodicity and duration, and also depends on the structure of the phase state of the metal membrane. It is shown that the diffusion coefficient increases when a narrow electron beam in the scanning regime is used. Analysis of the hydrogen yield as a function of time is carried out on a mass spectrometer connected to a vacuum chamber containing an electron gun, a beam sweep oscillator, and an electrolytic cell. The hydrogen diffusion coefficients under the action of a scanning electron beam are 15 times larger than under the same conditions without irradiation.

Nuclear reactions in the Pd/PdO:Dx and Ti/TiO2:Dx systems excited by ionizing radiation

The yield of the products of nuclear reactions from deuterated palladium and titanium irradiated by an electron beam and X rays has been studied. Charged particles have been detected by CR-39 track detectors, which are not sensitive to electronic noise, electrons, and X-ray photons. To identify the type of particles and to estimate their energy, three detectors covered by aluminum and copper foils of various thicknesses have been used. It has been established with reliable statistics that 30-keV electrons and X rays initiate the synthesis of deuterons in the Pd/PdO:Dx and Ti/TiO2:Dx systems with the yield of 3-MeV protons.

A laboratory device for measuring the diffusion coefficient of hydrogen in metals during their simultaneous hydrogenation and electron irradiation

An upgraded high-vacuum installation and procedure for studying diffusion of hydrogen in a BT1-0 titanium alloy membrane during irradiation of a sample by an electron beam with an energy of 10-120 keV in the scanning and stationary modes and with simultaneous electrolytic saturation are described. For this purpose, deflecting electrodes intended for scanning the beam are additionally integrated into the installation. The mass spectrum of the residual gases was recorded by the partial pressure sensors with a sensitivity as high as 10-13 Pa. The diffusion coefficient of hydrogen measured under the scanning action of the electron beam on the titanium membrane is given.

Thermo-Electromotive Force and Electrical Resistivity of Hydrogenated VT1-0 Titanium Alloy

The method for measuring the structure transition of hydrogenated titanium from one state to another is suggested. The method is based on the comparison of thermo-electromotive force (thermo-emf), DC electrical resistance and the results of X-ray diffraction analysis. X-ray diffraction analysis is applied for identifying the quantity of defects in titanium structure. The authors have also identified the identical dependence of thermo-electromotive force and electrical resistivity on hydrogen concentration in titanium. The effect can be used for hydrogenated titanium structure control.

Ultrasonic testing for hydrogen for titanium-based materials and articles

The propagation of ultrasonic (US) waves in hydrogen-saturated alloy based on VT1-0 titanium is investigated. Two characteristic domains of the effect of hydrogen on velocity VR of US waves are established. A characteristic peak observed on the dependence of the velocity of US waves on the hydrogen concentration makes it possible to determine the hydrogen concentration in titanium at which hydrogen embrittlement begins.

Hydrogen migration in metals under the combined action of acoustic and ionizing radiation

The hydrogen migration in metals under the action of ionizing and acoustic radiation is considered. The joint action of ionizing and acoustic radiation is found to enhance the hydrogen migration in metals (“interference” effect). The hydrogen transport mechanism is determined by the interaction of ionizing radiation with the hydrogen subsystem of a metal and a vibrodiffusion effect.