Observations of temperature stability of γ-zirconium hydride by high-resolution neutron powder diffraction

The phase evolution in a zirconium–50 deuterium (Zr–50D, at.%) alloy system during thermal cycling has been investigated using in situ high-resolution neutron powder diffraction. The results showed that the peritectoid reaction α-Zr + δ-ZrD → γ-ZrD previously suggested to occur at high temperatures does not take place in the system. Slow cooling, from high temperatures (≥520 K) to room temperature at a rate of 5 K min−1, promoted the γ-hydride formation rather than fast cooling as reported earlier. In contrast to the observation that the δ-hydride present in the system remained at temperatures up to 740 K, the produced γ phase transformed to δ-hydride in the temperature range of 370 K–559 K, with the transformation completing at approximately 559 K. It is confirmed that the formation of the γ-hydride was reproducible with slow cooling, and a diffusion-controlled sluggish δ-to γ-hydride transformation is suggested to be responsible for the favorable development of γ-hydride during slow cooling. © 2015 Elsevier B.V.

Keywords

Neutron diffraction, Phase transformations, Metals, Hydrides, Zirconium, Alloys

Citation

Wang, Z., Steuwer, A., Liu, N., Maimaitiyili, T., Avdeev, M., Blomqvist, J., Bjerkén, C., Curfs, C., Kimpton, J. A., & Daniels, J. E. (2016). Observations of temperature stability of γ-zirconium hydride by high-resolution neutron powder diffraction. Journal of Alloys and Compounds, 661, 55-61, doi:10.1016/j.jallcom.2015.11.187