Anisotropic co-deformation behavior of nanolamellar structures in additively manufactured eutectic high entropy alloys
Bibliographic record
Abstract
Laser-based directed energy deposition (DED) technique provides new opportunities for fabricating eutectic high entropy alloys (EHEAs) with directional nanolamellar structures that exhibit superior mechanical properties. The mechanisms of co-deformation, strengthening, fracture of the two constituent phases, and their resulting anisotropic mechanical properties, have not yet been systematically studied. Here we employ in situ synchrotron-based high-energy X-ray diffraction and X-ray tomography to study a DED-fabricated nanolamellar AlCoCrFeNi2.1 that is comprised of face-centered cubic (fcc) and ordered body-centered cubic (B2) phases. The EHEA samples that are loaded along three orientations present obvious mechanical anisotropy: (i) Samples HEA0, loaded along the lamellar direction, exhibit both the highest tensile strength and ductility; (ii) Samples HEA45, loaded along a 45-degree angle with the lamellar direction, exhibit the lowest strength and medial ductility; (iii) Samples HEA90, perpendicular to the lamellar direction, exhibit the medial strength and lowest ductility. We find that such mechanical anisotropy is associated with the sequence of work hardening in the B2 and fcc phases, as well as martensitic transformation in the B2 phase. For HEA0 samples, the sequential events of martensitic transformation of the B2 phase and work hardening of the fcc phase prevent from the initial fracture of the samples. In contrast, for the HEA90 samples, the simultaneous events of work hardening of both the B2 and fcc phases promote the formation and propagation of cracks along the phase boundaries, facilitating the fracture of the samples. This study demonstrates that the DED-produced EHEAs exhibit the optimal strength-ductility synergy along the lamellar direction and provides a fundamental understanding of the co-deformation behavior of dual phases in directional nanolamellar structures.
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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) | 0.000 | 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 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".