Microstructural characterization of the as-cast and annealed Pu-10Zr alloy

Assel Aitkaliyeva, Cynthia A. Adkins, Jacob Hirschhorn, Casey McKinney, Michael Tonks, Fidelma Giulia Di Lemma

Research output: Contribution to journalArticle

Abstract

Phase diagrams constructed for the Pu-Zr binary system report the existence of θ-(Pu,Zr), δ-(Pu,Zr), γ-Pu, α-Pu, β-Pu, and ζ-Pu28Zr phases in Pu-enriched region, when Pu concentrations exceed 75 at.% (equivalent to 89 wt% Pu). The compound θ-(Pu,Zr) has been said to occur at about 20 at.% Zr, but the regions for θ-(Pu,Zr) on the Pu-rich side have not been well defined. In an effort to understand the phases formed in Pu-Zr binary alloys and define the boundary between θ-(Pu,Zr), (θ+δ), and δ-(Pu,Zr) regions, Pu-10Zr (in wt.%, equivalent 23 at.%) alloys were scrutinized in this contribution. This manuscript details microstructural characterization and phase identification results obtained using electron microscopy-based techniques for a Pu-10Zr alloy before and after annealing at 550 °C. In contradiction with predicted phase diagrams, no θ-(Pu,Zr) was detected in any of the examined specimens. The phases present in as-cast fuel included a δ-(Pu,Zr) matrix with a number of smaller, randomly distributed α-Zr, ZrO2, Zr3O, PuO, and κ-PuZr2 inclusions. Heat treatment annealed out the intermetallic κ-PuZr2 phase and resulted in formation of small δ′-Pu and β-Pu inclusions. Similar to the as-cast alloys, the matrix of the annealed alloys was consistent with δ-(Pu,Zr) phase and contained small α-Zr, ZrO2, and PuO2 inclusions. Two different microscopy-based techniques were used for phase identification, but neither identified any θ-(Pu,Zr) phase. Differential scanning calorimetry was then used to determine the phase transition temperatures and enthalpies of transition for the identified phases. While our data is similar to the existing phase diagrams, a number of discrepancies are reported that call for a careful re-examination of the Pu-Zr system. This contribution discusses different scenarios that could explain the discrepancies between obtained and historical data, and provides the most logical conclusion that could be reached based on the obtained results.

Original languageEnglish (US)
Pages (from-to)80-90
Number of pages11
JournalJournal of Nuclear Materials
Volume523
DOIs
StatePublished - Sep 1 2019

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casts
phase diagrams
inclusions
Phase diagrams
cast alloys
binary alloys
matrices
intermetallics
Binary alloys
electron microscopy
heat treatment
heat measurement
examination
enthalpy
transition temperature
Electron microscopy
Superconducting transition temperature
Intermetallics
microscopy
Differential scanning calorimetry

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

Cite this

Aitkaliyeva, A., Adkins, C. A., Hirschhorn, J., McKinney, C., Tonks, M., & Di Lemma, F. G. (2019). Microstructural characterization of the as-cast and annealed Pu-10Zr alloy. Journal of Nuclear Materials, 523, 80-90. https://doi.org/10.1016/j.jnucmat.2019.05.051
Aitkaliyeva, Assel ; Adkins, Cynthia A. ; Hirschhorn, Jacob ; McKinney, Casey ; Tonks, Michael ; Di Lemma, Fidelma Giulia. / Microstructural characterization of the as-cast and annealed Pu-10Zr alloy. In: Journal of Nuclear Materials. 2019 ; Vol. 523. pp. 80-90.
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Aitkaliyeva, A, Adkins, CA, Hirschhorn, J, McKinney, C, Tonks, M & Di Lemma, FG 2019, 'Microstructural characterization of the as-cast and annealed Pu-10Zr alloy', Journal of Nuclear Materials, vol. 523, pp. 80-90. https://doi.org/10.1016/j.jnucmat.2019.05.051

Microstructural characterization of the as-cast and annealed Pu-10Zr alloy. / Aitkaliyeva, Assel; Adkins, Cynthia A.; Hirschhorn, Jacob; McKinney, Casey; Tonks, Michael; Di Lemma, Fidelma Giulia.

In: Journal of Nuclear Materials, Vol. 523, 01.09.2019, p. 80-90.

Research output: Contribution to journalArticle

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T1 - Microstructural characterization of the as-cast and annealed Pu-10Zr alloy

AU - Aitkaliyeva, Assel

AU - Adkins, Cynthia A.

AU - Hirschhorn, Jacob

AU - McKinney, Casey

AU - Tonks, Michael

AU - Di Lemma, Fidelma Giulia

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Aitkaliyeva A, Adkins CA, Hirschhorn J, McKinney C, Tonks M, Di Lemma FG. Microstructural characterization of the as-cast and annealed Pu-10Zr alloy. Journal of Nuclear Materials. 2019 Sep 1;523:80-90. https://doi.org/10.1016/j.jnucmat.2019.05.051