Solidification Structures in Low-Alloyed Powder Metallurgy Steels Obtained through Permanent Liquid Phase Sintering Using a Master Alloy Containing Boron
Bibliographic record
Abstract
Abstract Powder metallurgy (PM) steels containing boron form an attractive group of alloys because of the important densification that can be achieved through permanent liquid phase sintering (LPS). However, upon solidification, such liquid phase is known to form borides or borocarbides. Recent works have shown that some alloying elements have significant interactions with the LPS of PM steels containing boron. More specifically, it is suspected that the concentration of prealloyed molybdenum influences the formation of boride/borocarbide upon cooling at the end of the sintering cycle. Therefore, the main objective of this work is to describe the relationship that exists between the concentration of prealloyed molybdenum and the crystal structure of the boride/borocarbide eutectic component that typically forms in PM steels containing boron. A master alloy made of iron-manganese-nickel-boron-carbon was utilized to introduce boron, thus providing enhanced sintering through LPS. Characterization in optical and scanning electron microscopy combined with electron-backscattered diffraction and energy-dispersive X-ray spectrometry (EDS) revealed that increasing the prealloyed molybdenum content not only increased the volume fraction of liquid phase but also modified the morphology and the nature of the boron-rich eutectic. Changing the prealloyed molybdenum content from 0.5 to 0.85 wt.% transformed the discontinuous M2B boride to a continuous M23(C,B)6 borocarbide phase, causing a drastic decrease in strength despite the higher densification observed at 0.85 wt.% molybdenum. The effect of molybdenum on the LPS process of boron PM steels is undeniable and was found to occur after the initial formation of the liquid phase. Indeed, differential scanning calorimetry revealed no difference in the endothermic melting peaks temperature for both concentration of molybdenum.
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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 | 0.000 |
| 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".