Design criteria for single-phase non-equiatomic refractory multiprincipal element alloys from the Nb-Ti-Zr system
Bibliographic record
Abstract
• Design criteria for stable, single-phase refractory high entropy alloys from Nb-Ti-Zr system are established. • Combinational synthesis enabled screening through large portion of the Nb-Ti-Zr system. • Dissolved oxygen is the primary factor destabilizing the desired single-phase BCC structure. • Ti-rich compositions had higher oxygen tolerance than Zr-rich ones, despite similar oxygen solubility. Refractory high entropy alloys (RMPEAs) hold promise as candidate materials for high-temperature applications challenging widely used nickel-based superalloys. RMPEAs application is currently limited by their low structure and phase stability in the presence of oxygen, which can be improved by single-phase alloy design. This study establishes design criteria for achieving single-phase, non-equiatomic RMPEAs through a systematic exploration of the Nb-Ti-Zr compositional space. Using combinatorial synthesis via magnetron co-sputtering and high-throughput characterization, we map phase stability across a broad compositional range. We identify a stable single-phase BCC region for compositions containing 19.5–55 at.% Nb, 43–59 at.% Ti, and less than 30.5 at.% Zr. Monte Carlo simulations were used to predict the phase formation at high temperatures along with electron microscopy revealing phase segregations at high-Zr compositions, exploring the role of soluble oxygen in phase formation. Our findings provide a foundation for the rational alloy design, explain the effect of each element, and pave a path for further exploration and modification of the identified compositional space.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".