Evaluation of the Mechanical Properties of Naturally Grown Multilayered Oxides Formed on HCM12A Using Small Scale Mechanical Testing

Abad, M.D.; Parker, Stephen S.; Frazer, D.; Figueiredo, M. Rebelo de; Lupinacci, A.; Kikuchi, Kenji; Hosemann, Peter

doi:10.1007/s11085-015-9551-6

Cited by 20 publications

(8 citation statements)

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“…The system is a natural evolution of instrumented indentation with load and depth sensing 12,13 that has enabled significant micro-and nanoscale mechanical testing across a wide array of applications 14,15 and material properties. [16][17][18] In situ capabilities provide the ability to watch the deformation of the micro-or nanoscale specimen in real time, and also provide atmospheric control through the vacuum of the microscope. Cryogenic in situ micromechanical testing is a more recent capability, with only a handful of custom-built systems available.…”

Section: Introductionmentioning

confidence: 99%

Cryogenic Stress-Driven Grain Growth Observed via Microcompression with in situ Electron Backscatter Diffraction

Frazer

Bair

Homer

et al. 2020

JOM

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The deformation of materials at cryogenic temperature is of interest for space, arctic, and fundamental science applications. In this work, a custom-built cooling system attached to a commercial picoindenter was used for in situ cryogenic microcompression testing of equal-channel angular-pressed copper with real-time electron backscatter diffraction. Stress-driven grain growth at cryogenic temperatures was observed during a series of elastic and plastic deformations. These results provide direct evidence for the previously predicted phenomenon, whereas previous ex situ examinations demonstrated coarsening after cryogenic loading when samples were not maintained at cryogenic temperatures between deformation and characterization.

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Section: Introductionmentioning

confidence: 99%

Cryogenic Stress-Driven Grain Growth Observed via Microcompression with in situ Electron Backscatter Diffraction

Frazer

Bair

Homer

et al. 2020

JOM

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“…Micro-mechanical testing offers a unique tool to assess the response of thin surface layers, due to its ability to probe mechanical properties of specimens at µm length scales with high spatial resolution. This has been extensively utilised for numerous thin film and coating systems [38][39][40][41], but so far only a very limited number of studies have been performed on surface oxide scales [42][43][44] in order to estimate their fracture and elastic properties.…”

Section: Introductionmentioning

confidence: 99%

Microscale fracture of chromia scales

et al. 2019

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Native protective oxide scales offer resistance against corrosion for high temperature materials, which often work in extreme conditions of varying mechanical and thermal loads. The integrity of such layers is of critical importance, since their damage can lead to significant reduction in material life. Mechanical data such as fracture strain and elastic modulus are required to include oxides in material life estimation models for high temperature materials, but there is lack of such data. Their thickness is in the µm range, which makes mechanical testing for property determination difficult. Here we present a micro-mechanical testing method, based on bending of micro-cantilevers produced by focused ion beam milling, capable of circumventing the limitations of conventional approaches. We apply this method to chromia thermally grown on pure chromium, and measure fracture strains at room and high temperatures (600 °C). The measured fracture strains were found to be higher at room temperature, due to a larger fraction of transgranular fracture. Surprisingly, a large fraction of transgranular fracture was seen even in the presence of stress concentrations at grain boundaries. Removal of the stress concentrations accentuated the propensity for transgranular cracking at room temperature. Realistic values of room temperature elastic modulus were 2 obtained as well. The observed mixed trans-and intergranular cracking points towards the need for dedicated investigations of both oxide grain boundary strength and cleavage resistance of single crystals in order to fully understand the failure mechanisms in thermally grown oxide scales.

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“…The grown alumina scales are transient polymorphs that gradually transform into stable alumina [40] implying a volumetric change of ~14% in transformation from γ-Al 2 O 3 into α-Al 2 O 3 [41]. Spinel oxides have low thermal conductivity, while magnetite (Fe 3 O 4 ) is reported to tend to spall off [37,42]. Spalling is reported also for Al 2 O 3 protective scales [19, 33, 34, 36 and 43].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the thermal expansion coefficient mismatch between the oxides and the bulk might also contribute to the oxide spalling, in cooling at the end of heat transfer systems operation. Abad et al investigated the binding strength between the oxide layers and metals by using small scale mechanical testing [42], but the strain in the metal upon cooling of oxidized 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 samples has not been evaluated. It may be responsible for breaking and spalling of oxide layers especially if thermal cycling (as in solar thermal applications) is considered [47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

A study of deformation and strain induced in bulk by the oxide layers formation on a Fe-Cr-Al alloy in high-temperature liquid Pb-Bi eutectic

et al. 2018

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At elevated temperatures, heavy liquid metals and their alloys are known to create a highly corrosive environment that causes irreversible degradation of most iron-based materials. It has been found that an appropriate concentration of oxygen in the liquid alloy can significantly reduce this issue by creating a passivating oxide scale that controls diffusion, especially if Al is present in Fe-based materials (by Al-oxide formation). However, the increase of the temperature and of oxygen content in liquid phase leads to the increase of oxygen diffusion into bulk, and to promotion of the internal Al oxidation. This can cause a strain in bulk near the oxide layer, due either to mismatch between the thermal expansion coefficients of the oxides and bulk material, or to misfit of the crystal lattices (bulk vs. oxides). This work investigates the strain induced into proximal bulk of a Fe-Cr-Al alloy by oxide layers formation in liquid lead-bismuth eutectic utilizing synchrotron X-ray Laue microdiffraction. It is found that internal oxidation is the most likely cause for the strain in the metal rather than thermal expansion mismatch as a two-layer problem.Dear Sir, I re-submit our paper entitled: "A study of deformation and strain induced in bulk by the oxide layers formation on a Fe-Cr-Al alloy in high-temperature liquid Pb-Bi eutectic" on behalf of all co-authors to Acta Materialia, after addressing all the revisions stated by the reviewer. In the study, we analyze a strain in the near-interface bulk of ferritic FeCrAl alloy after its exposure to heavy liquid metals. Two possible origins of strain were considered: internal oxidation of aluminum in bulk, and thermal expansion mismatch between the oxide and the bulk. A positive correlation of dislocation density with peak width distribution indicates that strain comes from plastic deformation, while the evidence of grain refinement and sub-grain formation indicates a noticeable internal oxidation. Based on the comparison with theoretical predictions, we conclude that internal oxidation is more dominant mechanism of strain induction.Sincerely, Miroslav P. Popovic, UC Berkeley Cover LetterWe thank the reviewer for his/her time and effort.Below we address all reviewer's comments (labeled "C") in detail, marked in green (labeled "A").C 0: -Dear authors, congratulations for this interesting work.A 0: We thank the reviewer for his/her assessment of our paper. C1-1: You are studying the deformation and strain induced in the bulk of a Fe-Cr-Al alloy (Alkrothal 720) by oxide scales that form in liquid LBE. Alkrothal is a bcc alloy, a fact that you should clearly mention when you describe the material in the Experimental section (not just mention that it is a ferritic alloy), giving some basic information on the lattice parameters. A1-2: We thank the reviewer for this suggestion. We made changes in the manuscript and modified our statement (in the first paragraph of section 2. Experimental), so it reads now as following: C1-2. What you neglect to mention, however, is th...

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Evaluation of the Mechanical Properties of Naturally Grown Multilayered Oxides Formed on HCM12A Using Small Scale Mechanical Testing

Cited by 20 publications

References 63 publications

Cryogenic Stress-Driven Grain Growth Observed via Microcompression with in situ Electron Backscatter Diffraction

Cryogenic Stress-Driven Grain Growth Observed via Microcompression with in situ Electron Backscatter Diffraction

Microscale fracture of chromia scales

A study of deformation and strain induced in bulk by the oxide layers formation on a Fe-Cr-Al alloy in high-temperature liquid Pb-Bi eutectic

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