National Research Nuclear University MEPhI, Moscow, Russia:

I. I. Chernov, Professor at the Department of Nuclear Physics and Technology at the Office for Educational Programmes, Doctor of Physics & Mathematics Sciences, e-mail: i_chernov@mail.ru
M. S. Staltsov, Associate Professor at the Department of Nuclear Physics and Technology at the Office for Educational Programmes, Candidate of Physics & Mathematics Sciences, e-mail: m.staltsov@gmail.com

This paper presents the third part of a three-part review that looks at the effect of doping elements on the behaviour of helium and hydrogen, the development of gas porosity, as well as the amount of hydrogen retained in alloys of vanadium with Ti, Cr, W and Ta. This paper describes the results of a study that looked at the microstructure along the path of implanted helium ions. The samples were studied with the help of scanning electron microscopy (SEM). Three layers were detected in which helium porosity developed differently along the depth of the irradiated target. It was found that under sequential irradiation with helium and hydrogen ions pores/bubbles of maximum size tend to arise at distances from the surface exceeding the depth of the calculated distribution maximum of implanted helium ions. It means that as the result of additional Н⁺ ion irradiation of samples that were prior implanted with Не⁺ ions, the region of coarse porosity shifts deeper into the sample. The authors carried out a comparative study of and calculated the gas porosity parameters in samples produced in an electrolytic jet thinning unit on a non-irradiated side (TenuPol-5) and cut out perpendicular to the irradiated surface with a focused ion beam. It is shown that when using the electrolytic jet thinning unit all information deeper than 100 nm is lost, and when the focused ion beam was applied, porosity was detected at depths that exceed by almost 3 times the maximum calculated path of Не⁺ ions with a 40 keV energy in vanadium. It is noted that the key advantage of the focused ion beam method is the possibility to study the distribution of bubbles, pores, radiation defects and other objects along the depth of the irradiated layer, which provides a richer description of the microstructural development trends in simulation experiments involving ion irradiation. High cost and long SEM sample preparation time should be noted as the drawback of this method.

1. Chernov I. I., Staltsov M. S. Behaviour of helium and hydrogen in vanadium alloys – innovative fusion reactor first wall materials: a review. Part 1. V – Ti and V – Fe alloys. Tsvetnye Metally. 2022. No. 12. pp. 65–72.
2. Staltsov M. S., Chernov I. I., Kalin B. A. et al. Gas porosity along the ion path in vanadium and its alloys under sequential radiation with helium and hydrogen ions. Radiation solid body physics: Proceedings of the 28^th International Conference. Russia, Sevastopol, 09–14 July 2018. Moscow : Izdatelstvo FGBNU “NII PMT”, 2018. pp. 40–49.
3. Kalin B. A., Staltsov M. S., Chernov I. I. Gas porosity formed along the depth of low-activation vanadium alloy specimens during ion implantation of helium and hydrogen. Interaction between Plasma and the Surface: Proceedings of the 22^nd conference. Moscow, National Research Nuclear University MEPhI, 23–24 January 2019. pp. 67, 68.
4. Staltsov M. S., Chernov I. I., Kalin B. A. et al. Gas porosity forming along the ion path in vanadium alloys under sequential radiation with helium and hydrogen ions. Metally. 2019. No. 6. pp. 14–20.
5. Chernov I. I., Staltsov M. S., Kalin B. A. et al. Mechanism of helium porosity formation in the surface layer of fusion reactor first wall materials. Metally. 2016. No. 2. pp. 29–34.
6. Bondarenko G. G. Radiation physics, structure and strength of solid bodies. Moscow : Laboratoriya znaniy, 2016. 462 p.
7. Tetelbaum D. I., Bayankin V. Ya. Long-range effect. Priroda. 2005. No. 4. pp. 9–17.
8. Staltsov M. S., Chernov I. I. Behaviour of helium and hydrogen in vanadium alloys – innovative fusion reactor first wall materials: a review. Part 2. Alloys of vanadium with chromium, tungsten, tantalum. Tsvetnye Metally. 2023. No. 5. pp. 56–64.
9. Neustroev V. S., Makarov E. I., Belozerov S. V. et al. Effect of tensile and compressive stresses on the radiation swelling and creep deformation of austenitic steel Kh18N10T. Fizika metallov i metallovedenie. 2010. Vol. 110, No. 4. pp. 412–416.
10. Kinev E. A., Panchenko V. L. Swelling of 16Cr-15Ni-2Mo-Mn-Ti-V-B improved steel under dose rate from 1·10^–8 to 1.7·10^–6 dpa/s. Izvestiya vuzov. Yadernaya Energetika. 2017. No. 1. pp. 63–72.

11. Portnykh I. A., Kozlov A. V. The method of quantitative analysis of radiation porosity in metals. Voprosy atomnoy nauki i tekhniki. Series: Materials Science and Novel Materials. 2002. Iss. 1, No. 59. pp. 1–54.
12. Utke I., Hoffmann P., Melngailis J. Gas-assisted focused electron beam and ion beam processing. Journal of Vacuum Science and Technology. Series B. 2008. pp. 1197–1276.
13. Volkov R. L., Borgardt N. I., Kukin V. N. et al. Use of focused ion beam to prep specimens for surface nanostructure electron microscopy studies. Journal of Surface Investigation. X-Ray, Synchrotron and Neutron Techniques. 2011. No. 9. pp. 94–99.
14. Staltsov М. S., Chernov I. I., Korshunov S. N., Lagov P. B. Parameters of helium porosity in vanadium alloys when using different SEM sample preparation techniques: A comparison of study results. Metally. 2020. No. 2. pp. 51–57.
15. Staltsov М. S., Chernov I. I., Kalin B. A. et al. Peculiarities of helium bubble formation and helium behavior in vanadium alloys of different chemical composition. Journal of Nuclear Materials. 2015. Vol. 461. pp. 56–60.
16. Staltsov M. S., Chernov I. I., Aung Kyaw Zaw et al. Gas porosity formation in the vanadium alloys V–W, V–Ta, V–Zr during helium-ion irradiation at 650 ^oC. Atomic Energy. 2014. Vol. 116, No. 1. pp. 35–41.
17. Aparina N. P., Guseva M. I., Kolbasov B. N. et al. Certain aspects of the long-range effect. Voprosy atomnoy nauki i tekhniki. Termoyadernyi Sintez. 2007. Iss. 3. pp. 18–27.