Tomsk State University, Tomsk, Russia

S. V. Gunther, Senior Researcher, Candidate of Technical Sciences
A. N. Monogenov, Senior Researcher, Candidate of Physical and Mathematical Sciences
A. V. Vetrova, Research Engineer, Postgraduate Student, e-mail: aniuta-vetrova@mail.ru
M. A. Kovaleva, Laboratory Assistant, Student

The results of influence of the size factor on the structure, physical and mechanical properties of wire samples of alloys based on titanium nickelide are presented.Microstructur e analysis showed a direct dependence of strength properties on the average grain size. It is shown that as the wire diameter decreases from 3 to 0.04 mm, the average grain size decreases from 3 to 0.085 μm, respectively. Histograms of grain size distribution depending on the wire diameter from the alloy in question were constructed. The ratio of the volume of the oxide layer to the total volume of the wire increases with decreasing diameter of the wire samples and its influence intensifies. The size factor does not affect martensitic shear stress. Using X-ray microanalysis of the elemental composition, it was shown that the B2 phase, with a decrease in the diameter of the TiNi alloy wire from 3 to 0.04 mm, becomes depleted in titanium, which leads to an increase in the yield strength and, as a consequence, to higher mechanical characteristics. The tensile strength values were 670 and 1190 MPa for wires with a diameter of 3 and 0.04 mm, respectively. In the course of a comparative analysis of Vickers microhardness, an increase in microhardness (from 456 to 502 HV) was established depending on the diameter of the wire samples. The influence of the size factor on dissipative losses during martensitic transformations is a decrease in the width of the hysteresis loop with a decrease in the diameter of the wire made of an alloy based on titanium nickelide.
The structure studies were carried out using the equipment of the Tomsk Regional Center for Collective Use of the National Research Tomsk State University. The center is supported by the Grant of the Ministry of Science and Higher Education of the Russian Federation No. 075-15-2021-693 (No. 13.TSKP.21.0012).
The study was supported by a grant from the Russian Science Foundation (RSF), No. 19-72-10105, https://rscf.ru/project/19-72-10105/.

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