Radiation Damage Effect on Mechanical Properties and Microstructure of X-750 Ni-based Superalloy
Bibliographic record
Abstract
Inconel X-750 is an age-hardened Ni-based superalloy with high mechanical strength and creep resistance. The X-750 alloy is extensively used in the cores of reactors, such as spacers in CANada Deuterium Uranium (CANDU) fuel channels. The recent mechanical tests on the ex-service Inconel X-750 spacers indicate significant embrittlement and reduced load carrying capacity compared to as installed condition. The primary degradation mechanism remains unclear, and thus provides the focus of this investigation. Heavy-ion irradiation was employed as an emulator for neutron irradiation to explore the microstructural evolution and mechanical property degradation in X-750 Ni-based superalloy. The ion-irradiation has been conducted at different temperatures and up to different doses. In addition, helium-implantation prior to heavy-ion irradiation was used to investigate the effect of helium on microstructural changes. The discussion of the microstructural evolution is focused on characterization of irradiation-induced defects, including dislocation loops and cavities along with examination of the stability of strengthening phase γ'-precipitates. A major contribution of this work is to utilize a focused ion beam (FIB) and transmission electron microscopy (TEM) to perform precise defect characterization. The microstructure is correlated to the mechanical properties obtained via nano-hardness test on irradiated materials. In order to estimate the individual contribution of defects in radiation-induced hardening, three different obstacle-hardening models have been applied to fit TEM-obtained microstructural data. The superposition of contributions is made in each model and compared with nano-scale experimental results. This approach is unique to the literature since it demonstrates both the individual and the combined effects of the microstructural features on mechanical behavior. Furthermore, the effect of gamma-prime instability on mechanical properties of irradiated X-750 was investigated and the strength softening raised from disordering and also dissolution of gamma-prime was evaluated.
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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 | 0.001 | 0.000 |
| 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".