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ArticleName Сhanges of α-Zr grain orientations under thermal creep tests
ArticleAuthor Isaenkova M. G., Perlovich Yu. A., Fesenko V. A., Soe San Thu, Peregud M. M.

National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, Russia:
M. G. Isaenkova, Professor, e-mail:
Yu. A. Perlovich, Leading Researcher
V. A. Fesenko, Researcher
Soe San Thu, Post-Graduate Student
M. M. Peregud, Senior Researcher


The creep of products, made of Zr-based alloys, determines the duration of their possible usage by preservation of initial structure and texture. This article is devoted to research of instability of substructure condition and texture of cladding tubes, made of Zr – 1 % Nb alloy, at their exploitation temperature. The noticeable, formerly unobserved varying of crystallographic α-Zr texture takes place by thermal creep tests of tubes under internal pressure at the temperatures of 300–450 оС. This varying consists of changes of integral texture Kearns parameters, surely influencing the radiation behavior of tubes. First of all, changes of the tube texture under creep tests are the result of plane twinning {1012}, leading to abrupt reorientation of α-Zr grains with turn of their basal axes by 85o from tangential direction. This reorientation is the most intensive at the temperatures of 380–400 оС. Along with twinning, weakening the tangential component in tube texture, there is one more distinct tendency, which becomes apparent in tubes under creep tests. It consists in strengthening of the basal texture component by means of redistribution of basal axes to the radial direction as a result of more active slip by basal planes, favored by creep conditions. Besides, rotation of prismatic axes around the basal one testifies that the prismatic slip is among creep mechanisms. Greatest changes of the crystallographic texture are observed at outside layers of tested tubes. Thus, the thermal creep initiates the following deformation mechanisms: basal slip, prismatic slip and twinning. Their activity essentially depends on conditions of creep tests (temperature and stress).

keywords Zirconium alloy, thermal creep, deformation mechanisms, twinning, slip, crystallographic texture, shell tube

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