Korolev Samara National Research University, Samara, Russia

I. A. Zorin, Research Assistant of Sector-Specific Research Laboratory No. 4, Master’s Student, e-mail: zorin.ia@ssau.ru
A. M. Drits, Lead Researcher of Sector-Specific Research Laboratory No. 4, Candidate of Technical Sciences, e-mail: dritsam@gmail.com

Korolev Samara National Research University, Samara, Russia¹ ; Siberian State Industrial University, Novokuznetsk, Russia²
E. V. Aryshenskii, Senior Researcher of the Research Laboratory of Electron Microscopy and Image Processing², Lead Researcher of Sector-Specific Research Laboratory No. 4¹, Doctor of Technical Sciences, Associate Professor, e-mail: ar-evgenii@yandex.ru
S. V. Konovalov, Vice-Rector for Research and Innovation², Chief Researcher of Sector-Specific Research Laboratory No. 4¹, Doctor of Technical Sciences, Professor, e-mail: konovalov@sibsiu.ru

The authors studied the effect of hafnium additives on the structure and properties of alloy 1570 in a cold rolled state. Alloy 1570 and its similar alloy with added 0.2 % Hf were homogenized at 370 ^oC for 4 h. The transmission electron microscopy study on a fine structure showed that in a homogenized state of alloy 1570 – 0.2 Hf an addition of 0.2% Hf to alloy 1570 contributed to finely dispersed L12 Al3Sc precipitates mainly with a nominal diameter of 7.2 nm, and an average particle diameter for alloy 1570 was 10 nm, while its total volume demonstrated a decrease as compared with alloy 1570. The homogenized samples of alloys 1570 and 1570 – 0.2 Hf underwent hot and cold rolling, whose total reduction was 90%, and final annealing. A grain structure was studied with optical microscopy methods, which revealed no signs of recrystallization. Mechanical properties were tested for the cold rolled and annealed samples according to the following schedules: 340 ^oC — 1 h, 340 ^oC — 3 h, 440 ^oC — 1 h, and 440 ^oC — 3 h. Tests for mechanical properties showed that hafnium additives contributed to an increase in mechanical characteristics by 15–20 %. For example, after annealing at 340 oC and holding for 3 h, yield strength of the alloy with hafnium is higher by 49 MPa as compared with alloy 1570. When increasing annealing temperature, mechanical characteristics decrease both in nominal and absolute values. Main reasons for decreased mechanical properties are a return process and relevant annihilation of dislocations and coagulation of particles due to a temperature increase as the structure of the alloys under study is not recrystallized even after high temperature annealing. Properties of alloy 1570 – 0.2 Hf decrease slower due to the thermostabilizing effect of hafnium.
The research was funded by the Russian Science Foundation, project 22-29-01506, https://rscf.ru/project/22-29-01506/.

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