Deformation and rate controlling mechanisms in fine-grained magnesium
Bibliographic record
Abstract
The effect of grain size and deformation temperature on the deformation and rate-controlling mechanisms of commercially pure magnesium (CP-Mg) has been evaluated using a combination of mechanical response analysis, microstructure and texture studies, dislocation network analysis, and crystal plasticity modelling of work hardening. The effect of grain size on mechanical properties varies between room and cryogenic temperatures. Twinning and slip are dominant deformation modes in coarse-grained Mg at 298 K. A critical grain size of approximately 3 μ m marks a transition in deformation mechanisms, characterized by reduced slip and twinning activity and the promotion of grain boundary-mediated deformation coupled with intense dynamic recovery. At 78 K and 4 K, twinning and slip remain the primary deformation modes across all grain sizes, with dislocation-twin and dislocation-dislocation interactions acting as the primary work-hardening processes. Suppression of thermal activation, which facilitates deformation at 298 K, leads to more effective dislocation storage at cryogenic temperatures. Strain rate sensitivity measurements were conducted to understand the rate-limiting mechanisms during plastic flow of CP-Mg. The cross-slip of basal 〈 a 〉 and 〈 c + a 〉 dislocations characterized by activation volume of Δ V ∗ ≈ 16 b 3 and activation distance d ≈ 0 . 25 b is identified as the rate-controlling process in fine-grained Mg at 298 K during all stages of deformation and also occurs in coarse-grained magnesium at high strains. Transmission electron microscopy (TEM) studies provide independent data on the state of the dislocation microstructure, complementing the results of crystal plasticity modelling, and establishing a link between grain size and the mechanical properties of Mg between 4 K and 298 K.
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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".