Tula State University (TulGU), Tula, Russia¹ ; Metsintez Ltd., Tula, Russia²:

S. S. Volodko, Graduate Student of the Chair for Physics of Metals and Materials Science^1,2, e-mail: volodko.sv@yandex.ru

Tula State University (TulGU), Tula, Russia:
G. V. Markova, Head of the Chair for Physics of Metals and Materials Science, Doctor of Technical Sciences, e-mail: galv.mark@rambler.ru

Metsintez Ltd., Tula, Russia:
A. V. Kasimtsev, Director, Doctor of Technical Sciences, e-mail: metsintez@yandex.ru

NUST MISiS, Moscow, Russia:

A. V. Korotitsky, Senior Researcher, Candidate of Physical and Mathematical Sciences, e-mail: akorotitskiy@gmail.com

The deformation behavior of the Ti_29.7Ni_50.3Hf₂₀ powder alloy under conditions of high-temperature uniaxial compression in the temperature range 700–1000 ^oC and strain rates in the range ε = 0.003–30 s^–1 was studied. It is shown that at small deformations the stress strains of resistance increase sharply with increasing the degree of deformation (elastic region). Then, on the deformation diagram in the region of the elastic-plastic transition, a maximum of stresses (σ_p) was observed, which, depending on the temperature-velocity conditions of the process, is followed by either the stage of metal steady flow or the stage of softening. The presence of a stress peak on the deformation diagram may indicate the beginning of a dynamic recrystallization process. In experiments, the effect of deformation heating (ΔT) is observed, which affects the nature of the deformation diagrams. At ε = 0.3 s^–1, ΔT leads to the wavy nature of the deformation curves, and at ε = 330 s–1, it leads to softening as the deformation accumulates in the sample. The maximum value of ΔT = 120 ^oC was recorded for the deformation temperature of 700 ^oC and ε = 3 s^–1. The minimum values of ε are observed in the temperature range 800–1000 ^oC and strain rates ε = 0.003–0.3 s^–1. This area can be considered as the most preferred in terms of thermomechanical treatment of the Ti_29.7Ni_50.3Hf₂₀ powder alloy. The data obtained as a result of the experiment made it possible to derive an analytical equation capable of predicting the values of material flow stresses within the experiment factor space. It is shown that the obtained model adequately describes the deformation behavior of the investigated alloy, and the relative error between the experimental and calculated values does not exceed 6%.
The study was performed with the financial support of the Russian Foundation for Basic Research within the research project No. 20-38-90238.

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