Neutron Irradiation Effect on the Hardness of Nickel Titanium Alloy Modified by Krypton Ions

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BRIEF COMMUNICATIONS NEUTRON IRRADIATION EFFECT ON THE HARDNESS OF NICKEL TITANIUM ALLOY MODIFIED BY KRYPTON IONS V. P. Poltavtseva,1 A. S. Larionov,1 and S. A. Gyngazov2

UDC 539.173.5

Keywords: titanium nickelide, krypton, neutron irradiation, microhardness, electrical resistivity.

INTRODUCTION The development of nickel titanium (NiTi) alloys resistant to ionizing radiation is rather relevant to the materials science field [1–4]. Our previous research [5, 6] shows that megaelectron-volt energy irradiation with krypton and xenon ions is the most effective method of creating the hardened nanolayers in NiTi alloy products for medical applications. The investigation of the coating-hardened NiTi alloy resistance to neutron irradiation is of great interest to researchers. The aim of this work is to investigate the influence of neutron irradiation on the NiTi alloy properties in different initial states before and after its modification by megaelectron-volt krypton ion beams. In these investigations we utilize the microhardness and electrical resistivity measurements.

MATERIALS AND METHODS The NiTi alloy specimens in martensitic-austenitic and austenitic conditions were prepared for radiation resistance testing before and after their modification by krypton ions (84Kr15+) on a DС-60 heavy-ion accelerator at the L. N. Gumilyov Eurasian National University (Nur-Sultan, Republic of Kazakhstan) [5]. The process parameters for the DС-60 included 147 MeV energy, 11019 ion/m2 fluence, 100°С temperature. Earlier [5, 6] we showed that the phase composition of the NiTi alloy specimens in martensitic-austenitic and austenitic conditions changed after the 84Kr15+ irradiation at 100°С owing to the martensite-to-austenite phase transformation, viz. В19' → В2. The neutron irradiation was performed on a VVR-K research reactor (Almaty, Republic of Kazakhstan) with low enriched fuel in a vertical channel. The irradiation temperature did not exceed 60°С, the fluence was 2.31016 and 1.51015 neutrons per cm2 for thermal and fast neutrons, respectively. The microhardness testing was performed on a PMT-3М Vickers hardness tester (Russia). The hardening degree was estimated by the microhardness testing results, depending on the indentation depth under the load ranged between 0.098±4.9 N. The thickness of the measured layer was detected at each load application by the depth of indentation, and the average microhardness was determined by 5 or 7 indentation points. The microhardness measurement accuracy was 3–4%.

1

The Institute of Nuclear Physics of the Ministry of Energy of the Republic of Kazakhstan, Almaty, Kazakhstan, e-mail: [email protected]; [email protected]; 2National Research Tomsk Polytechnic University, Tomsk, Russia, e-mail: [email protected]. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 171– 173, July, 2020. Original article submitted April 2, 2020. 1064-8887/20/6307-1293 2020 Springer Science+Business Media, LLC

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TABLE 1. Phase Composition of NiTi Alloy, Neutron Irradiation Conditions and