National Research Nuclear University MEPhI, Moscow, Russia:

K. E. Klyukova, Engineer, Postgraduate Student
M. G. Isaenkova, Doctor of Physical and Mathematical Sciences, Professor, e-mail: isamarg@mail.ru
O. A. Krymskaya, Associate Professor, Candidate of Physical and Mathematical Sciences
V. A. Fesenko, Research Fellow

This paper examines the processes of recrystallization in sheets of Zr – 2.5% Nb alloy rolled down to a 50–90% deformation and annealed at 610 ^oC for 1, 3 and 5 hours. The heating rate varied from 10 to 100 ^oC/min. With the help of X-ray structure and texture analysis, the authors looked at optimizing the crystal structure of the deformed alloy while examining changes in the crystallographic texture. It was established that annealing of Zr – 2.5% Nb alloy sheets performed at the temperature that corresponds to the dual phase region α + β of an equilibrium phase diagram also leads to recrystallization, as it happens when applying the annealing temperature of 580 ^oC. However, an 11% increase in the concentration of the additional phase suppresses changes in the crystallographic texture, which may be due to the predominant precipitation of β-zirconium at grain boundaries. At the same time, the growth of recrystallized grains still follows the main regularities of orientation: the orientation of growing grains corresponds to the texture maximum slopes of the direct pole figure (0001); an increased pole density was observed on the difference charts of the direct pole figure {10.0}, which is indicative of the presence of grains that are disoriented to the deformed matrix at 30^o around the base normals. It is shown that the contribution of the above mentioned processes is determined by the type of initial texture, the annealing temperature, the heating rate and the amount of β-phase. An extended annealing time (from 1 to 5 hours) at the temperature of the dual phase region does not cause any significant change in the crystallographic texture.
This research was funded by the Ministry of Science and Higher Education of the Russian Federation; Agreement No. 075-15-2021-1352.

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