Abstract
The current work is devoted to developing a system for the complex research of metal–hydrogen systems, including in an in situ mode. The system consists of a controlled gas reactor with a unique reaction chamber, a radioisotope positron source, and a positron annihilation spectroscopy complex. The use of the system enables in situ investigation of the defect structure of solids in hydrogen sorption–desorption processes at temperatures up to 900 °C and pressures up to 50 bar. Experimental investigations of magnesium and magnesium hydride during thermal annealing were carried out to approve the possibilities of the developed complex. It was shown that one cycle of magnesium hydrogenation–dehydrogenation resulted in the accumulation of irreversible hydrogen-induced defects. The defect structure investigation of the magnesium–hydrogen system by positron annihilation techniques was supplemented with a comprehensive study by scanning electron microscopy, X-ray diffraction analysis, and hydrogen sorption–desorption studies.
Highlights
Academic Editors: Xingzhong Cao, The study and control of metal–hydrogen systems have several specific features associated with the high hydrogen diffusion mobility in metals and alloys, and its high reactivity
Based on the diffraction pattern of the powder obtained after dehydrogenation, the less than 20 μm were observed, which did not have time to agglomerate into larger partiphase composition differs little from that of ground magnesium
Peaks corresponding to magnesium hydride are not present in the X-ray diffraction pattern
Summary
Academic Editors: Xingzhong Cao, The study and control of metal–hydrogen systems have several specific features associated with the high hydrogen diffusion mobility in metals and alloys, and its high reactivity. Hydrogen can interact with different complexes, including vacancy-type defects, impurity atoms, dislocations, intrinsic interstitial atoms, and grain boundaries [1–9]. The mechanisms of hydrogen’s effect on defects and the structural-phase state and mechanical properties of metallic materials have not been fully established despite numerous studies in this area. The development of new and improvement of known methods for controlling defects in metal–hydrogen systems is extremely urgent since there are still unresolved problems of the degradation of metals with hydrogen, and there is the need to create new functional materials for operation in hydrogen-containing environments [1–4]. For the early detection of hydrogen embrittlement of metals and alloys, it is crucial to control the interaction of dislocations and hydrogen-vacancy complexes. It is essential to establish the actual size and concentration of defects and identify the parameters influencing physical and mechanical properties. Positron spectroscopy methods are the most effective for monitoring the interaction of hydrogen with defects and revealing
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