A comparative study of carbon additives on grain refinement of magnesium alloys
Bibliographic record
Abstract
To overcome the shortcomings of the superheating process (e.g. the high operating temperature and the applicability to relatively small volumes of melt only), post-1940s research on the grain refinement of magnesium alloys foucsed on developing an alternative method applicable to large volumes of melt at low operating temperatures. These efforts led to the discovery of the carbon inoculation process. A number of carbon based additives were tested for their grain refining potential, for example carbonaceous gases, soluid carbon or carbon-bearing powders and silicon carbides.Following the discovery of the grain-refining effect of carbon additions, considerable efforts were made to develop a commercially reliable grain refiner for Mg-Al alloys. From an operational aspect, the carbonaceous gases and organic chlorides can be more readily introduced to magnesium melts than the solid carbon additives. In addition, bubbling a melt also helps to degas the melt. The addition of carbon in the form of C2Cl6 or Cl2-CCl4 blend was widely used before the 1970s because of the combined action of grain refining and degassing. The major problem of using carbonaceous gases, particularly chlorine-based gases, is the emission of chlorinated hydrocarbons (CHC). Other developments avoided gaseous additions. For example, Renger and Simon reported an effective grain refiner named Nucleant 5000, which appeared to work satisfactorily on AZ91 alloys. Wax-fluorspar-carbon grain refiners were developed earlier in England and recently in Canada. Liu et al. reported an Al4C3-SiC-Al alloy suitable for grain refinement of Mg-Al alloys such as AZ31 and AZ63. Motegi et al. recently disclosed a carbon grain refiner that contains either pure carbon powder or a mixture of carbon and Nb2O5 or V2O5 powder. However, to date no carbon-based grain refiners have proved reliable in delivering consistent grain refinement of Mg-Al alloys. This study compares the grain-refining effect of five carbon-based refiners provided by different suppliers (part of the experimental results were reported previously). The mechanism of grain refinement by carbon addition is discussed.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".