Study of dynamic grain growth by electron microscopy and EBSD

Rofman, O.V.; Bate, Pete S.; Brough, I.; Humphreys, F.J.

doi:10.1111/j.1365-2818.2009.03131.x

Cited by 14 publications

(11 citation statements)

References 22 publications

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“…12) Data from ''ex situ'' EBSD analysis are usually acquired from different areas of the same specimen and subsequently compared. This approach can lead to misinterpretation of the real state of microstructure, because the microstructure of severely plastically deformed material is inherently inhomogeneous.…”

Section: )mentioning

confidence: 99%

Study of Thermal Stability of Ultrafine-Grained Copper by means of Electron Back Scattering Diffraction

2010

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Thermal stability of ultrafine-grained (UFG) structure of 99.9% pure copper produced by eight equal channel angular pressing (ECAP) passes was studied. The annealing experiments were conducted at 180 C in a tube furnace under argon as a covering gas. The dwell times were in the range of 10 min to 120 min. The electron backscattering diffraction (EBSD) analyses were performed before and after annealing at exactly the same area in order to quantify the degree of decomposition of the UFG structure. Definition of grain boundaries was based on the misorientation angle of 1 . More advanced analysis of the EBSD results based on a kernel average misorientation (KAM) parameter was performed. Inverse pole figure maps with included grain networks did not reveal any substantial changes of UFG microstructure due to annealing. Some shift in the KAM modus in comparison with the initial state was observed but its magnitude was found negligible. Also changes in texture were found to be minor. On the other hand the microhardness increases with increasing time of annealing.

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Section: )mentioning

confidence: 99%

Study of Thermal Stability of Ultrafine-Grained Copper by means of Electron Back Scattering Diffraction

2010

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“…These energy states are affected by the state of crystal plastic deformation, too. Some experimental evidence indeed points towards "dynamic grain growth" even during diffusion creep [e.g., Wilkinson and Caceres, 1984;Kellermann Slotemaker et al, 2004;Rofman et al, 2009].…”

Section: Comparison To Previous Analytical Piezometric Relationsmentioning

confidence: 99%

High‐temperature deformation and recrystallization: A variational analysis and its application to olivine aggregates

Hackl

Renner

2013

JGR Solid Earth

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[1] We develop a framework for a variational analysis of microstructural evolution during inelastic high-temperature deformation accommodated by dislocation mechanisms and diffusive mass transport. A polycrystalline aggregate is represented by a distribution function characterizing the state of individual grains by three variables, dislocation density, grain size, and elastic strain. The aggregate's free energy comprises elastic energy and energies of lattice distortions due to dislocations and grain boundaries. The work performed by the external loading is consumed by changes in the number of defects and their migration leading to inelastic deformation. The variational approach minimizes the rate of change of free energy with the evolution of the state variables under constraints on the aggregate volume, on a relation between changes in plastic strain and dislocation density, and on the form of the dissipation functionals for defect processes. The constrained minimization results in four basic evolution equations, one each for the evolution in grain size and dislocation density and flow laws for dislocation and diffusion creep. Analytical steady state scaling relations between stress and dislocation density and grain size (piezometers) are derived for quasi-homogeneous materials characterized by a unique relation between grain size and dislocation density. Our model matches all currently available experimental observations regarding high-temperature deformation of olivine aggregates with plausible values for the involved micromechanical model parameters. The relation between strain rate and stress for olivine aggregates maintaining a steady state microstructure is distinctly nonlinear in stark contrast to the majority of geodynamical modeling relying on linear relations, i.e., Newtonian behavior.Citation: Hackl, K., and J. Renner (2013), High-temperature deformation and recrystallization: a variational analysis and its application to olivine aggregates,

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“…262 The emphasis herein has been on 3D spatial analysis, although time resolved studies are possible. It has been used to investigate recrystallization, 265 grain growth, 266,267 grain boundary migration, 268 phase transformation, 269 and deformation processes, [270][271][272] with a time resolution determined by the scan rate, which can be on the order of tens of seconds depending on the area being scanned and the resolution. Improvements in this area are likely to involve data acquisition as well as data manipulation.…”

Section: Advances In and Applications Of Serial Sectioningmentioning

confidence: 99%