Dependence of Thermal Expansion of Zr-Based Products on their Crystallographic Texture

The accident at Fukushima Daiichi in 2011 highlighted the increased interest in predicting the materials properties under extreme conditions. In this work, it is considered the behaviour of cubic samples cut from the wall of channel tubes made of Zr-2.5% Nb alloy during heating and cooling in the temperature range of 20-1200 °C. The anisotropy of changes in the dimensions of cubic samples in different structural states has been studied. Thermal tests were carried out in three mutually perpendicular directions: radial, tangential and axial. The structural state of tubes was estimated from the features of their crystallographic texture. The significant anisotropy of the size change is observed in the Zr-2.5%Nb alloy product with an unstable crystallographic texture of deformation due to the α↔β-phase transformation inhomogeneity. In the case of complete recrystallization and orientation of the axes along the tube axis, the anisotropy of the dimensions change is minimal, due to uniform nuclei formation of new phases in different orientations.