On Interfacial Ribbons of ζ- and γ-Hydride Phases Surrounding δ Precipitates in Zircaloy-2
Bibliographic record
Abstract
This study investigated the formation of ζ- and γ-hydride phases among furnace-cooled zirconium-hydride precipitates in Zircaloy-2. A previous in situ hydride precipitation experiment (conducted in 2018) suggested that both γ and δ hydrides are stable phases in Zircaloy-2 and can form simultaneously during the close-to-equilibrium conditions. To satisfy Gibbs’ phase rule, it was suggested that the coexistence between the γ and δ phases must take place through the formation of precipitates with a core-shell morphology (i.e., a δ core surrounded by a γ shell). A mechanism was also suggested to describe the formation of such core-shell precipitates, based on which an interfacial ribbon of ζ phase can also potentially form, surrounding the γ shell. In 2008, ζ phase was reported after the observation of unexpected electron diffraction patterns (DPs) and measurement of a plasmon energy (PE) value of 17.4 ± 0.2 eV for needle-shaped nanohydrides in Zircaloy-4. In this work, electron DPs of nanohydrides with similar morphology were characterized in several orientations, and it is shown that DPs previously interpreted as signatures of the ζ phase, in fact, can stem from the δ phase overlapped with either the α-Zr or a surface (probably zirconium-oxide) phase. This finding ruled out the formation of the interfacial ζ phase in our system. Moreover, electron energy-loss spectroscopy measurements revealed the existence of PE gradients across the interface between the α-Zr and δ core, including the PE values of the ζ and γ phases. The origin of the observed PE gradients was studied using electron diffraction and dielectric theory. It is suggested that the observed PE gradients likely stemmed from the delocalized nature of plasmon vibration and the variation of hydrogen concentration across the interface.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".