National University of Science and Technology “MISiS”, Laboratory “Hybrid Nanostructured Materials”, Moscow, Russia:
S. A. Nikulin, Head of a Chair of Metal Science and Physics of Strength, e-mail: nikulin@misis.ru
T. A. Nechaykina, Assistant Professor
A. B. Rozhnov, Assistant Professor
A. P. Baranova, Scientific Expert

In prospect, the fuel claddings in fast reactors may be manufactured by using layered composites based on vanadium alloy and ferritic (ferritic-martensitic) high-chromium steel. The characteristics of such composite are mainly defined by the structure and strength properties of the “transition” area, formed on the boundary of the composite’s constituent part during its obtaining. The subsequent thermal treatment (annealing) will influence the structural-phase state and durability of the “transition” area. We carried out the investigations of the influence of a two-hour annealing at the temperature of 800–900 ^oC (after co-extrusion at the temperature of 1100 ^oC) on structural-phase state and strength properties of the “transition” area of a vanadium alloy and steel compound. At the same time, we applied the light and electronic microscopy, X-ray diffractometry, and carried out mechanical testing of samples of the composite tube “steel 20Kh13/vanadium alloy V – 4% Ti – 4% Cr/steel 20Kh13”. Annealing at the temperature of 800–900 ^oC (after co-extrusion) increased the width of the “transition” area from 10 to 30 micron and equalized the chemical composition along the width. Redistribution of chemical elements in the “transition” area of interlayer attraction during thermal treatment does not lead to release of secondary phases and embrittlement of the zone where materials are welded together. At the temperature of 800–900 ^oC (two hours), the annealing of the composite’s samples favours the decomposition of martensite (formed after co-extrusion) and formation of recrystallized ferrite grains with the size of 45–70 microns along the whole section of the steel layer. A two-hour annealing of a multilayer composite at the temperature of 800–900 ^oC after co-extrusion does not lead to decreasing of the compound’s durability. After annealing in this temperature range, two-layer samples of composite are destructed by a tough patching mechanism without the formation of brittle cracks and layering near the compound area, which confirms the strength joint of component materials in a multilayer composite.
This work was carried out with the financial support of the Ministry of Education and Science of Russian Federation (unique ID No. RFMEFI57517X0124).

1. Kurtz R. J., Abe K., Chernov V. M., Hoelzer D. T., Matsui H., Muroga T., Odette G. R. Recent Progress on Development of Vanadium Alloys for Fusion. Journal of Nuclear Materials. 2004. Vol. 329–333. pp. 47–55.
2. Muroga T., Nagasaka T., Abe K., Chernov V. M., Matsui H., Smith D. L., Xu Z.-Y., Zinkle S. J. Vanadium Alloys — Overview and Recent Results. Journal of Nuclear Materials. 2002. Vol. 307–311. pp. 547–554.
3. Fukumoto K., Matsui H., Narui M., Yamazaki M. Irradiation creep behavior of V – 4 Cr – 4 Ti alloys irradiated in a liquid sodium environment at the JOYO fast reactor. Journal of Nuclear Materials. 2013. Vol. 437. pp. 341–349.
4. Chen J., Qiu S., Yang L., Xu Z., Deng Y., Xu Y. Effects of oxygen, hydrogen and neutron irradiation on the mechanical properties of several vanadium alloys. Journal of Nuclear Materials. 2002. Vol. 302. pp. 135–142.
5. Natesan K., Soppet W. K., Uz M. Effects of Oxygen and Oxidation on Tensile Behavior of V – 4 Cr – 4 Ti. Journal of Nuclear Materials. 1998. Vol. 258–263. pp. 1476–1481.
6. Matsushima T., Satou M., Hasegawa A., Abe K., Kayano H. Tensile properties of a series of V – 4 Ti – 4 Cr alloys containing small amounts of Si, Al and Y, and the influence of helium implantation. Journal of Nuclear Materials. 1998. Vol. 258–263. pp. 1497–1501.
7. Nikulin S. A., Votinov S. N., Rozhnov A. B. Vanadium alloys for nuclear energetic. Moscow : NITU “MISiS”, 2014. 206 p.
8. Nechaykina T. A., Nikulin S. A., Rozhnov A. B., Rogachev S. O., Votinov S. N., Gershteyn G. Structure and phase composition of transition zone of a three-layer material based on refractory vanadium alloy and ferritic steel. Metallovedenie i termicheskaya obrabotka metallov. 2015. No. 4. pp. 31–36.
9. Nikulin S. A., Rozhnov A. B., Nechaikina T. A., Rogachev S. O., Zavodchikov S. Yu., Khatkevich V. M. Structure and mechanical properties of the three-layer material based on a vanadium alloy and corrosion-resistant steel. Russian Metallurgy (Metally). 2014. No. 10. pp. 793–799.
10. Nechaykina T. A., Nikulin S. A., Rozhnov A. B., Khatkevich V. M., Rogachev S. O. Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel. Metallurgical and Materials Transactions A. 2017. Vol. 48, No. 3. pp. 1330–1342.
11. Kobelev A. G., Potapov I. N., Kuznetsov E. V. Technology of laminated metals. Moscow : Metallurgiya, 1991. 248 p.
12. Kobelev А. G., Lysak V. I., Chernyshev V. N., Bykov A. A., Vostrikov V. P. Production of metallic laminated composite materials. Moscow : Intermet Engineering, 2002. 496 p.
13. Shelekhov E. V., Sviridova T. A. Programs for X-ray analysis of polycrystals. Metal Science and Heat Treatment. 2000. Vol. 42. pp. 309–313.