Surface compressive and softening effect on deformation mode transition in Ni-Nb metallic glassy thin films: A molecular dynamics study
Bibliographic record
Abstract
Size-dependent deformation mode transition in metallic glasses (MGs) attracts a lot of interest due to potential application in micro-devices, but the underlying mechanisms are still unclear from the perspective of structure, e.g., how the chemical composition affects the deformation mode transition in a particular system is mysterious as well and needs to be addressed. Here, a series of NixNb100−x (x = 30, 50, 62, and 70 at. %) MG thin films has been studied by molecular dynamics simulations for better understanding the thickness-dependent tensile behaviors. The results show that the deformation mode transition from highly-localized to non-localized occurs as the film thickness (t) approaches the critical size, tc, which strongly correlates with the chemical composition, i.e., a Ni-rich specimen with higher modulus has smaller tc. It is revealed that the softening and compressive effect of surface layers with about 0.4 nm thickness in terms of Voronoi volume is the key factor for this transition regardless of composition. We illustrate the surface softening effect in various MG thin films by introducing a softening coefficient (Ψ) parameter reflecting the structural difference between the surface layer and the internal part. It is found that the higher the Ψ, the severer the surface softening effect, and the larger the tc in the Ni-depleted specimen, indicating the importance of Ψ as an indicator for the deformation mode transition.
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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 | 0.000 | 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".