Study of the Mechanisms of Radiation Softening and Swelling upon Irradiation of TiTaNbV Alloys with He2+ Ions with an Energy of 40 keV

Abstract

This paper presents simulation results of the ionization losses of incident He2+ ions with an energy of 40 keV during the passage of incident ions in the near-surface layer of alloys based on TiTaNbV with a variation of alloy components. For comparison, data on the ionization losses of incident He2+ ions in pure niobium, followed by the addition of vanadium, tantalum, and titanium to the alloy in equal stoichiometric proportions, are presented. With the use of indentation methods, the dependences of the change in the strength properties of the near-surface layer of alloys were determined. It was established that the addition of Ti to the composition of the alloy leads to an increase in resistance to crack resistance under high-dose irradiation, as well as a decrease in the degree of swelling of the near-surface layer. During tests on the thermal stability of irradiated samples, it was found that swelling and degradation of the near-surface layer of pure niobium affects the rate of oxidation and subsequent degradation, while for high-entropy alloys, an increase in the number of alloy components leads to an increase in resistance to destruction.

Study of The Gas-Swelling Mechanisms in Silicon Carbide Ceramics under High-Temperature Irradiation with Helium Ions

“…At the same time, for samples irradiated at a temperature of 1000 K, the appearance of single spherical inclusions, 150-200 nm in diameter and characteristic of the nucleation of gas-filled bubbles, is observed on the surface. The appearance of such inclusions indicates helium agglomeration in structural cavities, followed by their deformation and extrusion to the surface, which is in good agreement with several works [27,28]. The small size and the distance from each other of the formed bubbles indicate a sufficiently high resistance of ceramics to the formation of such inclusions at given irradiation fluences.…”

Identification of temperature and diffusion effects during helium swelling of the surface layer of a TiTaNbV alloy

“…At the same time, radiation damage resistance for high-entropy alloys is determined by the presence of structural distortions of the crystal lattice associated with the elemental composition of the alloys, which results in a slowdown in the diffusion of point and vacancy defects in the damaged layer compared to similar effects in austenitic alloys and stainless steels [19,20]. In this case, structural features associated with the presence of various elements in the composition of the alloys, as well as their equally probable arrangement in the crystal lattice, as a rule, determine the presence of structural distortions, which, as has been shown in a number of works [21][22][23], provide high strength indicators, and also in the case of radiation damage, restrain migration and diffusion processes, thereby reducing the rate of radiation-induced degradation of the nearsurface layer of alloys under long-term exposure. However, in this issue there are still a large number of points that require detailed study and consideration, both from the point of view of a fundamental understanding of the processes of radiation damage in high-entropy alloys, and from a practical point of view associated with conducting full-scale experiments that clearly demonstrate the behavior of materials under irradiation.…”

“…The study of the processes of gas swelling as a result of high-dose irradiation with helium ions (He 2+ ) was conducted in order to determine the connection between the established structural changes (strain distortion of crystal lattice parameters, volumetric swelling, changes in the concentration of defective inclusions) and strength parameters (changes in hardness, strength, dry friction coefficient), alterations in which imply radiation-induced surface erosion processes associated with swelling. The experiments were carried out on samples of high-entropy alloys TiTaNbV with a cubic type of crystal lattice, obtained using the method of arc melting of the elements Ti, Ta, Nb, V in equal stoichiometric ratios [23]. The starting elements were used in the form of powders with a chemical purity of about 99.95%; these powders were purchased from Sigma Aldrich (Sigma, USA).…”

“…Homogeneity of the alloy composition was achieved by sequential remelting over 5 cycles. Melting was carried out in vacuum (5 × 10 -5 mbar) [23]. As a result of similar procedures, TiTaNbV alloys were obtained with a body-centered type of crystal lattice, which has a pronounced textural direction (200), associated with the formation processes of these alloys (see x-ray diffraction results in figure 1).…”

“…The relevance of this study is to determine the influence of irradiation temperature not only on the structural disorder effects caused by the cumulative effects of structural distortions and deformations, but also to determine the diffusion processes on the softening (decrease in hardness) of the surface layer in a TiTaNbV alloy exposed to external influences. Previously, in [23], we carried out a series of experiments to establish the dependence of changes in structural and strength effects in the near-surface layer during helium irradiation of alloy samples with variations in the number of TiTaNbV alloy components. According to the studies, it was determined that the most resistant alloy to radiation embrittlement and swelling under high-dose irradiation with helium ions is the TiTaNbV alloy.…”