Phase transformations in metastable $\beta$ Zr15Nb alloy revealed by in-situ methods

Anna Veverková; Kristína Bartha; Jozef Veselý; Pere Barriobero-Vila; Jiří Kozlík; Petr Doležal; Jiří Pospíšil; Jana Šmilauerová; Josef Stráský

arXiv · 2511.09236

Phase transformations in metastable $\beta$ Zr15Nb alloy revealed by in-situ methods

Anna Veverková·Kristína Bartha·Jozef Veselý·Pere Barriobero-Vila·Jiří Kozlík·Petr Doležal·Jiří Pospíšil·Jana Šmilauerová·Josef Stráský

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Abstract

This study examines the phase transitions occurring during linear heating of the Zr15Nb alloy through a comprehensive, multi-technique methodology comprising in-situ high-energy synchrotron X-ray diffraction (HEXRD), electrical resistance measurements, differential scanning calorimetry (DSC), and thermal expansion analysis, supplemented by ex-situ transmission electron microscopy (TEM). The findings reveal a complex sequence of phase transformations and corresponding structural changes over a broad temperature range (from room temperature up to 800 ${\deg}$C). Two distinct body-centered cubic (bcc) $\beta$ phases - $\beta_{Zr}$ and $\beta_{Nb}$ - with closely related lattice parameters are identified. At room temperature, the microstructure is characterized by a mixture of the metastable $\beta_{Zr}$ + $\omega_{ath}$ phase. Upon heating, $\beta_{Zr}$ progressively decomposes, giving rise to the formation of $\beta_{Nb}$. TEM observation revealed the cuboidal shape of the $\omega_{iso}$ particles resulting from the high lattice misfit between $\beta$ and $\omega$ phase. The $\omega$ solvus temperature is determined to be approximately 555 ${\deg}$C, as evidenced by in situ HEXRD and abrupt changes in the alloy's thermal and electrical properties. The growth of the $\alpha$ phase occurs after the dissolution of the $\omega$ phase, resulting in a pronounced increase in thermal expansion.

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Anna Veverková, Kristína Bartha, Jozef Veselý, Pere Barriobero-Vila, Jiří Kozlík, Petr Doležal, Jiří Pospíšil, Jana Šmilauerová, Josef Stráský. 2025-11-12. Phase transformations in metastable $\beta$ Zr15Nb alloy revealed by in-situ methods. https://arxiv.org/abs/2511.09236

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