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The effect of irradiation temperature on damage structures in proton-irradiated zirconium alloys

DOI: 10.1016/j.jnucmat.2018.12.006 DOI Help

Authors: M. Topping (The University of Manchester) , A. Harte (University of Manchester) , T. Ungar (The University of Manchester; Eötvös University) , C. P. Race (The University of Manchester) , S. Dumbill (National Nuclear Laboratory) , P. Frankel (The University of Manchester) , M. Preuss (University of Manchester)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Journal Of Nuclear Materials

State: Published (Approved)
Published: December 2018

Abstract: A study into the effects of irradiation temperature on the damage structures that form during proton-irradiation has been carried out on two commercial Zr alloys in order to develop a more mechanistic understanding of the effect of niobium on dislocation loop evolution. The two Zr alloys (Zircaloy-2 and Low-Sn ZIRLO™) were proton irradiated to a damage level of ∼2 dpa at 280 °C, 350 °C and 450 °C. Detailed dislocation analysis was carried out using on-axis bright-field scanning transmission electron microscopy combined with spectral imaging and synchrotron x-ray line profile analysis. The analysis revealed a significant difference in the effect of irradiation temperature on loop size between the two alloys. In the case of the Nb-free Zr-alloy (Zircaloy-2), an increase in irradiation temperature results in a marked increase in a-loop diameter, by a factor of ∼7.5 from 280 to 450 °C, and a stark decrease in the dislocation line density. In contrast, the Nb-containing Zr-alloy (Low-Sn ZIRLO™) showed very little variation of loop size and line density over the same radiation temperature range. The STEM-based spectral imaging revealed irradiation-induced nano-clustering found throughout the matrix in Low-Sn ZIRLO™, which is not present in the case of Zircaloy-2. Therefore, it is proposed that Nb plays a crucial role in the evolution of dislocation loops in Zr through the formation of irradiation precipitation throughout the matrix.

Subject Areas: Materials

Instruments: I11-High Resolution Powder Diffraction

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