Nanoscale mechanisms of hydrogen segregation and diffusion in metals
Bibliographic record
Abstract
Hydrogen embrittlement (HE), a phenomenon known as hydrogen deteriorating mechanical properties of structural metals to cause premature failure, continues to haunt the industry in the design and application of structural metals since its first discovery more than one century ago.Despite continuous research effort on HE, there remains no consensus on the exact mechanism underlying the occurrence of HE.However, it is widely recognized that HE is microstructure-sensitive, namely microstructural heterogeneities play a vital role in determining the material's susceptibility to HE.This thesis represents a body of research studies dedicated to understanding the key mechanistic aspects underlying the interplay between microstructures and hydrogen in structural metals, in order to provide insights towards developing effective microstructure engineering routes to moderate or prevent HE.Focusing on two main categories of microstructural entities in structural metals, dislocations and grain boundaries, the thesis systematically investigated the interactions between hydrogen and microstructures at the atomic scale, employing comprehensive molecular dynamics simulations, first principles calculations and Kinetic Monte Carlo simulations.The simulation results were then interpreted in the framework of continuum mechanics to develop physics-based predictive models to reveal the structure-property relationships underlying energetics and kinetic behaviors of hydrogen at dislocations and grain boundaries.This thesis is in the manuscript-based format, composed of four articles shown in Chapter 4-7, including predictive assessments of hydrogen energetics and segregation at grain boundaries ont été proposés dans le but d'évaluer l'énergie et la cinétique de l'hydrogène dans les joints de grain et les dislocations.Cette thèse est présentée sous forme de manuscrit composé de quatre articles introduits dans les chapitres 4 à 7. Dans le chapitre 4, le spectre d'énergie de l'hydrogène demeurant à différents joints de grains examinés fut déterminé.Le chapitre 5 s'intéresse à la cinétique de l'hydrogène aux joints de grains.Dans le chapitre 6, le rôle de l'hydrogène sur la nucléation des dislocations est expliqué, et le chapitre 7 traite sur le piégeage et la diffusion de l'hydrogène dans les dislocations.Ces articles ont non seulement fourni une compréhension de l'énergie et de la cinétique de l'hydrogène dans les hétérogénéités microstructurales, mais ont également approfondi la compréhension mécanistique de la fragilisation de l'hydrogène.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".