High Resolution Studies of Dealloyed Layers
Bibliographic record
Abstract
The nanoscale morphology of dealloyed materials has been studied for many years, from Pickering and Swann [1], through A.J. Forty [2], to recent TEM and atom-probe studies [3, 4]. Modern instruments have the ability to reveal key features of dealloying at unprecedented resolution, as well as having facilities for heating and environment control. Our particular interest is the dealloying behaviour of ternary alloys, such as AgAuPt, following the recent work of Vega [5]. Another area of interest is stress corrosion cracking of such materials, which features film-induced brittle events [6, 7]. Progress will be reported in several areas, including – High-resolution ATEM studies of dealloyed binary and ternary alloys , to observe and account for the distributions of Ag, Au and Pt for various dealloying conditions (binary AgPt is included in this part of the study). In situ heating studies of dealloyed binary and ternary alloys , to gain more insight into the observations of Vega [8] regarding oxygen-induced surface segregation of Pt, and other ways to manipulate the surface composition of the ligaments within the nanoporous material. Conventional underpotential deposition and novel “sub”-potential deposition of bulk Cu , as shown by Lee et al. for deposition of Cu into dealloyed CuPt [9]. Pore-filling of dealloyed materials by electrodeposition , often believed to be impossible, but actually a relatively easy method, provided the conditions are controlled very precisely and one is only dealing with a surface layer. Naturally this method is more challenging for ternary than binary alloys, owing to the smaller pore size. Copper is the initial metal of choice for pore filling. Atom-probe tomography studies are in progress, as favourable sites within the sample can be chosen for tip fabrication, even when pore filling is uneven. Initial results show good promise as a way to determine definitively the elemental distributions. References [1] H. W. Pickering and P. R. Swann. Electron metallography of chemical attack upon some alloys susceptible to stress corrosion cracking, Corrosion , 1963, 19 , 373t. [2] A. J. Forty. Corrosion micro-morphology of noble-metal alloys and depletion gilding, Nature , 1979, 282 , 597. [3] B. Pfeiffer, T. Erichsen, E. Epler, C. A. Volkert, P. Trompenaars, and C. Nowak. Characterization of nanoporous materials with atom probe tomography, Microscopy and Microanalysis, 2015, 21 , 557-563. [4] T. Fujita, P. Guan, K. McKenna, X. Lang, A. Hirata, L. Zhang, T. Tokunaga, S. Arai, Y. Yamamoto, N. Tanaka, Y. Ishikawa, N. Asao, Y. Yamamoto, J. Erlebacher and M. Chen. Atomic origins of the high catalytic activity of nanoporous gold, Nature Materials , 2012, 11 , 775–780. [5] A. A. Vega and R. C. Newman. Nanoporous metals fabricated through electrochemical dealloying of Ag-Au-Pt with systematic variation of Au:Pt ratio. Journal of the Electrochemical Society , 2014, 161 , C1-C10. [6] Andrew Barnes, N.A. Senior and R. C. Newman. Film-induced cleavage of Ag-Au alloys. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science , 2009, 40 , 58-68. [7] S. Sun, X. Chen, N. Badwe and K. Sieradzki. Potential-dependent dynamic fracture of nanoporous gold. Nature Materials , 2015, 14 , 894-898. [8] A. A. Vega and R. C. Newman. Beneficial effects of adsorbate-induced surface segregation of Pt in nanoporous metals fabricated by dealloying of Ag-Au-Pt alloys. Journal of the Electrochemical Society , 2014, 161 , C11-C19. [9] L. Lee, D. He, A.G. Carcea and R.C. Newman. Exploring the reactivity and nanoscale morphology of de-alloyed layers. Corrosion Science, 2007, 49 , 72–80.
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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".