Uncovering the mechanism behind a two-step infiltration during layered wide-gap brazing of a Ni-base superalloy using a B-Containing filler metal
Bibliographic record
Abstract
This study investigates the mechanisms resulting in a two-step infiltration process during layered wide-gap brazing of the MAR-M247/BNi-9 system for repair of high-temperature Ni superalloy components. Differential scanning calorimetry was coupled with electron microscopy and 3D X-ray microscopy to better quantify the two-step infiltration process. It was found that significant diffusional homogenization between braze alloy and MAR-M247 particles, occurred prior to liquation. As a result, only about 15% of the braze melted during Stage 1 of layered wide-gap brazing as compared to approximately 49% when only the melting of pure BNi-9 was considered for the same temperature interval. Stage 1 melting began at the ternary eutectic transformation temperature, 1053 °C, with the complete melting of Ni 3 B and partial melting of γ -Ni. Upon liquation, the braze liquid readily infiltrated the MAR-M247 skeleton via capillary action. As a result of rapid boron diffusion into the MAR-M247 skeleton from the infiltrating braze, extensive base metal dissolution and eventual diffusional solidification occurred, with Stage 1 infiltration terminating at 1073 °C. Stage 2 melting and infiltration began at 1102 °C with the re-melting of the partially infiltrated braze as well as melting of remaining un-infiltrated braze atop the layered brazement, with near complete infiltration attained by 1150 °C. Further, it was found that infiltration behavior varied between Stages 1 and 2, with 58% and 40% of the MAR-M247 skeleton infiltrated after 120 s and 228 s, respectively. Kinetic differences were likely influenced by: (i) transition from rapid to sluggish skeletal dissolution regimes, and an (ii) alteration of the MAR-M247 pore network structure
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".