Pathways for Hydrogen Absorption into Zircaloy-2 under Cathodic Polarization Assessed by Scanning Electrochemical Microscopy, Scanning Electron Microscopy, and Electrochemical Impedance Spectroscopy
Bibliographic record
Abstract
Hydrogen absorption by Zircaloy-2 has been studied in neutral sodium sulfate solutions using steady-state polarization measurements, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM). For applied potentials < −1 V (vs. saturated calomel electrode, SCE), water reduction occurs in faults in the passive oxide covering the alloy. For potentials ≤−1.3 VSCE, SECM detects a distribution of reactive locations on the electrode surface. Matched SECM and SEM images of the same electrode surface show more reactive sites to be located in the β-phase grain boundaries than on the α-grains. The reactivity of surface locations was determined using SECM probe approach curves. Secondary phase particles incorporating impurities such as Fe, Ni, and Cr as Zr(Fe, Cr)2 and Zr2(Fe, Ni) are particularly reactive spots, which may act as "windows" for hydrogen absorption into the alloy. This claim is supported by the observation that the surface of the α-grains remains passive even at potentials as low as −2.0 VSCE. The need to include a Warburg impedance element in modeling EIS recorded at potentials ≥−1.3 VSCE suggests that H2O reduction is confined to tight flaws in the oxide at grain boundary locations.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 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".