Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Fundamentals of substructure dynamics: In-situ experiments and numerical simulation
Stockholm University, Faculty of Science, Department of Geological Sciences. (Petrotectonics)
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Substructure dynamics incorporate all features occurring on a subgrain-scale. The substructure governs the rheology of a rock, which in turn determines how it will respond to different processes during tectonic changes. This project details an in-depth study of substructural dynamics during post-deformational annealing, using single-crystal halite as an analogue for silicate materials. The study combines three different techniques; in-situ annealing experiments conducted inside the scanning electron microscope and coupled with electron backscatter diffraction, 3D X-ray diffraction coupled with in-situ heating conducted at the European Radiation Synchrotron Facility and numerical simulation using the microstructural modelling platform Elle. The main outcome of the project is a significantly refined model for recovery at annealing temperatures below that of deformation preceding annealing. Behaviour is highly dependent on the temperature of annealing, particularly related to the activation temperature of climb and is also strongly reliant on short versus long range dislocation effects. Subgrain boundaries were categorised with regard to their behaviour during annealing, orientation and morphology and it was found that different types of boundaries have different behaviour and must be treated as such. Numerical simulation of the recovery process supported these findings, with much of the subgrain boundary behaviour reproduced with small variation to the mobilities on different rotation axes and increase of the size of the calculation area to imitate long-range dislocation effects. Dislocations were found to remain independent to much higher misorientation angles than previously thought, with simulation results indicating that change in boundary response occurs at ~7º for halite. Comparison of 2D experiments to 3D indicated that general boundary behaviour was similar within the volume and was not significantly influenced by effects from the free surface. Boundary migration, however, occurred more extensively in the 3D experiment. This difference is interpreted to be related to boundary drag on thermal grooves on the 2D experimental surface. While relative boundary mobilities will be similar, absolute values must therefore be treated with some care when using a 2D analysis.

Place, publisher, year, edition, pages
Stockholm: Department of Geological Sciences, Stockholm University , 2010. , 23 p.
Series
Meddelanden från Stockholms universitets institution för geologiska vetenskaper, 342
Keyword [en]
halite, in-situ, X-ray diffraction, EBSD, annealing, substructure, modelling
National Category
Earth and Related Environmental Sciences
Research subject
Geology
Identifiers
URN: urn:nbn:se:su:diva-45811ISBN: 978-91-7447-187-8 (print)OAI: oai:DiVA.org:su-45811DiVA: diva2:369878
Public defence
2010-12-20, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:30 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.Available from: 2010-11-28 Created: 2010-11-11 Last updated: 2010-12-03Bibliographically approved
List of papers
1. Post-deformational annealing at the subgrain scale: Temperature dependent behaviour revealed by in-situ heating experiments on deformed single crystal halite
Open this publication in new window or tab >>Post-deformational annealing at the subgrain scale: Temperature dependent behaviour revealed by in-situ heating experiments on deformed single crystal halite
2010 (English)In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 32, no 7, 982-996 p.Article in journal (Refereed) Published
Abstract [en]

The dynamics of substructures, which encompass all structures present at the subgrain-scale, were investigated by static, in-situ annealing experiments. Deformed, single crystal halite was annealed inside a scanning electron microscope at temperatures between 280-470 ºC. Electron backscatter diffraction maps provided detailed information about crystallographic orientation changes. Three temperature dependent regimes were distinguished based on boundary misorientation changes. In regime I (280-300 ºC) some low angle boundaries (LABs), i.e. with 1º-15º misorientation, increase in misorientation angle, while others decrease. In regime II (~300 ºC) all LABs undergo a decrease in misorientation angle. Regime III (>300 ºC) is defined by enhancement of the subgrain structure as remaining LABs increase and some undergo a rotation axis change. Throughout regimes I and II, new LABs develop, subdividing subgrains. LABs could be divided into four categories based on annealing behaviour, orientation and morphology. We suggest that these observations can be directly related to the mobility and activation temperature of climb of two dislocation groups introduced during deformation. Therefore, with in-depth investigation of a substructure with known deformation geometry, we can infer ratios of dislocation types and their post-deformation and post-annealing location. These can potentially be used to estimate the post-deformational annealing temperature in crystalline materials.

Keyword
halite, annealing, EBSD, substructure, in-situ
National Category
Geology
Research subject
Geology
Identifiers
urn:nbn:se:su:diva-45682 (URN)10.1016/j.jsg.2010.06.006 (DOI)000283687500009 ()
Available from: 2010-11-10 Created: 2010-11-10 Last updated: 2017-12-12Bibliographically approved
2. The application of in-situ 3D X-ray Diffraction in annealing experiments: First interpretation of substructure development in deformed NaCl
Open this publication in new window or tab >>The application of in-situ 3D X-ray Diffraction in annealing experiments: First interpretation of substructure development in deformed NaCl
Show others...
2010 (English)In: Recrystallization and Grain Growth: Proceedings of the fourth Joint International Conference of Recrystallization and Grain Growth, 2010Conference paper, Published paper (Refereed)
Abstract [en]

In-situ 3D X-ray diffraction (3DXRD) annealing experiments were conducted at the ID-11 beamline at the European Synchrotron Radiation Facility in Grenoble. This allowed us to non-destructively document and subsequently analyse the development of substructures during heating, without the influence of surface effects. A sample of deformed single crystal halite was heated to between 260-400 ºC. Before and after heating a volume of 500 by 500 by 300 mm was mapped using a planar beam, which was translated over the sample volume at intervals of 5-10 µm in the vertical dimension. In the following we present partially reconstructed orientation maps over one layer before and after heating for 240min at 260 ºC. Additional small syn-heating “maps” over a constrained sample rotation of 12-30º. The purpose of this was to illuminate a few reflections from 1 or 2 subgrains and follow their evolution during heating.

Preliminary results show that significant changes occurred within the sample volume, for which, surface effects can be excluded. Results show a number of processes, including: i) change in subgrain boundary misorientation angle and ii) subgrain subdivision into areas of similar lattice orientation with new subgrain boundary formation. These results demonstrate that 3DXRD coupled with in-situ heating is a successful non-destructive technique for examining real-time post-deformational annealing in strongly deformed crystalline materials with complicated microstructures.

Keyword
halite, annealing, X-ray diffraction, substructure, in-situ
Research subject
Geology
Identifiers
urn:nbn:se:su:diva-45688 (URN)
Conference
Recrystallization and Grain Growth
Available from: 2010-11-10 Created: 2010-11-10 Last updated: 2010-11-12Bibliographically approved
3. In-situ 3DXRD annealing of a geological material: Evaluating the validity of 2D 
Open this publication in new window or tab >>In-situ 3DXRD annealing of a geological material: Evaluating the validity of 2D 
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Most in-situ heating experiments where substructure is investigated have been restricted to 2D. We compare a 2D experiment to a 3D X-ray diffraction experiment to evaluate the validity of the 2D method. Until now 3D X-ray diffraction has been limited to well-recovered substructures. We conducted a 3D in-situ annealing experiment on a halite crystal with a significant orientation gradient. This is the first experiment of its kind on a geological material and shows that even complicated microstructures can be resolved. Comparison of 2D and 3D showed that, although general results were similar, subgrain boundary movement occurred with higher frequency in 3D. We suggest this discrepancy is due to enhanced drag force on subgrain boundaries by surface thermal grooving. Thus, while results from 2D experiments largely reflect what is happening in the volume, analysis of boundary movement with regard to absolute mobilities needs to be considered with some care.

Research subject
Geology
Identifiers
urn:nbn:se:su:diva-45685 (URN)
Available from: 2010-11-10 Created: 2010-11-10 Last updated: 2010-11-30Bibliographically approved
4. Numerical simulation coupled with in-situ annealing experiments: A new model for recovery
Open this publication in new window or tab >>Numerical simulation coupled with in-situ annealing experiments: A new model for recovery
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A new, deterministic model for recovery integrated with the microstructural modelling platform Elle is presented here. Experimental data collected from 2D in-situ annealing experiments were used to develop and verify the simulation. The model is based on the change of strain energy related to misorientation when a virtual rotation is applied to a crystallite (i.e. physical data point). Boundary energies are calculated using the Read-Shockley relationship. The axes of rotation were selected based on the deformation geometry and potentially activated slip systems. Crystallographic rotation was applied in the case where largest reduction of energy was observed. The effect of parameters such as rotation mobility, neighbourhood size, critical misorientation and specific energy calculation method were systematically investigated. Simulations reproduced many aspects of the experiments and showed that processes were highly dependent on dislocation type and increase of long-range effects with temperature. The results suggest that dislocations remain independent entities for longer than expected, even in an organised subgrain boundary. The model could not, however, retain higher angle boundaries and always resulted in a general shift of boundary distributions towards lower angles. We suggest that the classic interpretation of boundary energies does not entirely work for misorientations that lie in the less defined part of the Read-Shockley relationship.

Research subject
Geology
Identifiers
urn:nbn:se:su:diva-45687 (URN)
Available from: 2010-11-10 Created: 2010-11-10 Last updated: 2010-11-12Bibliographically approved

Open Access in DiVA

kappa_borthwick(14678 kB)537 downloads
File information
File name FULLTEXT01.pdfFile size 14678 kBChecksum SHA-512
05c00568fe58dbbf0a6d6547466cc01a723d7f67357dfaabf8d30da0a1459eeabb311aae2628a59ab0cca0a05dc1b98dd8d35491a0e525959679147f5f73af51
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Borthwick, Verity
By organisation
Department of Geological Sciences
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 537 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 495 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf