Grain Subdivision of a Nb Polycrystal Deformed by Successive Compression Tests

2010 ◽  
Vol 667-669 ◽  
pp. 373-378
Author(s):  
Liang Zhu ◽  
Hugo Ricardo Zschommler Sandim ◽  
Marc Seefeldt ◽  
Bert Verlinden
Keyword(s):  
Grain Boundary ◽  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Small Strain ◽  
The Other ◽  
Polycrystalline Materials ◽  
Historical Evolution ◽  
Compression Tests ◽  
Electron Backscatter ◽  
Backscatter Diffraction

To understand and model grain refinement in severe plastic deformation, some analysis of Nb single crystals has been carried out in previous work. To bridge the gap with normal polycrystalline materials, supplementary experiments on large polycrystals, deformed at moderate strains appear to be necessary to explain the grain subdivision step by step. In the present work, successive uniaxial compression tests have been carried out on a large grained Niobium polycrystal up to height reductions of 30% with small strain increments. Electron backscatter diffraction (EBSD) analysis was done after each compression step to characterize the evolution of orientation and microstructures. It is observed that a “rotation front” forms inside the grain and moves with increasing strain from one side to the other side of the grain. In one grain, this process results in a grain boundary affected zone in the vicinity of the grain boundary. Both static orientation evolution inside the grain and historical evolution of the average orientation have been studied, which indicates that the grain orientation rotates around one of the (110) poles at low strain.

Application of Electron Backscatter Diffraction to Grain Boundaries

2010 ◽  
Vol 160 ◽  
pp. 39-46 ◽  
Author(s):  
Valerie Randle
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Experimental Methodology ◽  
Polycrystalline Materials ◽  
Grain Boundary Engineering ◽  
Network Characteristics ◽  
Grain Boundary Plane ◽  
Electron Backscatter ◽  
Measurement Strategies ◽  
Backscatter Diffraction

The technique of electron backscatter diffraction (EBSD) is ideal for the characterisation of grain boundary networks in polycrystalline materials. In recent years the experimental methodology has evolved to meet the needs of the research community. For example, the capabilities of EBSD have been instrumental in driving forward the topic of ‘grain boundary engineering’. In this paper the current capabilities of EBSD for grain boundary characterisation will be reviewed and illustrated by examples. Topics are measurement strategies based on misorientation statistics, determination of grain boundary plane distributions and grain boundary network characteristics.

Electron backscatter diffraction investigation of local misorientations and orientation gradients in connection with evolution of grain boundary structures in deformed and annealed zirconium. A new approach in grain boundary analysis

2013 ◽  
Vol 46 (2) ◽  
pp. 483-492 ◽  
Author(s):  
Mariusz Jedrychowski ◽  
Jacek Tarasiuk ◽  
Brigitte Bacroix ◽  
Sebastian Wronski
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Lattice Defect ◽  
Line Segments ◽  
Compression Direction ◽  
Electron Backscatter ◽  
Grain Orientation Spread ◽  
Backscatter Diffraction

The main aim of the present work is to study the relation between microstructural features – such as local misorientations, grain orientation gradients and grain boundary structures – and thermomechanical treatment of hexagonal zirconium (Zr702α). Electron backscatter diffraction (EBSD) topological maps are used to analyze the aforementioned material parameters at the early stages of plastic deformation imposed by channel-die compression, as well as at a partial recrystallization state achieved by brief annealing. The evolution of local misorientations and orientation gradients is investigated using the so-called kernel average misorientation (KAM) and grain orientation spread (GOS) statistics implemented in the TSLOIMdata analysis software [TexSEM Laboratories (2004), Draper, UT, USA]. In the case of grain boundaries (GBs) a new method of analysis is presented. As an addition to the classical line segments method, where the grain boundary is represented by line segments that separate particular pairs of neighboring points, an approach that focuses on grain boundary areas is proposed. These areas are represented by sets of EBSD points, which are specially selected from a modified calculation procedure for the KAM. Different evolution mechanisms of intragranular boundaries, low-angle grain boundaries and high-angle grain boundaries are observed depending on the compression direction. The observed differences are consistent with the results obtained from KAM and GOS analysis. It is also concluded that the proposed method of grain boundary characterization seems to be promising, as it provides new and interesting analysis tools such as textures, absolute fractions and other EBSD statistics of the GB areas. This description may be more compatible with a real deformed microstructure, especially for grain boundaries with very small misorientation, which are indeed clustered areas of lattice defect accumulation.

Grain Boundary Self-Diffusion in Nickel

2007 ◽  
Vol 263 ◽  
pp. 207-212 ◽  
Author(s):  
Vĕra Rothová ◽  
Jiří Buršík ◽  
Milan Svoboda ◽  
Jiří Čermák
Keyword(s):  
Grain Boundary ◽  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Coincidence Site Lattice ◽  
Self Diffusion ◽  
Electron Backscatter ◽  
Cold Rolled ◽  
Backscatter Diffraction ◽  
Arrhenius Temperature ◽  
Diffusion Profiles

Grain boundary self-diffusion in both the cast and the cold-rolled Puratronic 4N5 nickel was studied in the temperature range from 600 °C to 1000 °C. The experiments were carried out with the samples pre-annealed at 1100 °C in comparison to the samples pre-annealed at intended individual diffusion temperatures. The relative grain orientation was analyzed on the same samples by means of electron backscatter diffraction (EBSD) and grain boundaries (GBs) were characterized in terms of the coincidence site lattice (CSL) model. Considering the non-linear Arrhenius temperature dependencies obtained for most specimens by using conventional method of profile evaluation in the B-type kinetics and the appearance of two high-diffusivity paths in diffusion profiles measured, a more suitable BB-type and AB-type diffusion models were applied for data evaluation.

Electron backscatter diffraction determination of grain orientation and constituent phases

1999 ◽  
Vol 4 (2) ◽  
pp. 174-174
Author(s):  
Chen Xiaomei ◽  
Liu Jing ◽  
Wang Jianbo ◽  
Zhang Ruikang ◽  
Wang Dahai ◽  
...  
Keyword(s):  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Diffraction Determination ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Comparison of Workability of ZK60A Alloy Depending on Casting Methods

2012 ◽  
Vol 630 ◽  
pp. 35-40
Author(s):  
K.H. Jung ◽  
B. Ahn ◽  
S. Lee ◽  
D.S. Choi ◽  
Y.S. Lee ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Continuous Casting ◽  
Elevated Temperatures ◽  
Electron Backscatter Diffraction ◽  
Die Casting ◽  
Inspection System ◽  
Compression Tests ◽  
X Ray ◽  
Electron Backscatter ◽  
Backscatter Diffraction

In this research, the effect of casting methods on the workability of magnesium alloy ZK60A was investigated by comparing two different billets, fabricated by semi-continuous casting and die casting. To determine the workability of the materials, uniaxial compression tests were conducted at different elevated temperatures and strain rate of 0.01/s. In addition, the X-ray inspection system and electron backscatter diffraction (EBSD) were employed to compare their internal defects and microstructures, respectively. The workability of ZK60A depending on the casting methods is discussed based on the obtained experimental results.

scholarly journals Coupling Automated Electron Backscatter Diffraction with Transmission Electron and Atomic Force Microscopies

2000 ◽  
Vol 6 (S2) ◽  
pp. 940-941
Author(s):  
A.J. Schwartz ◽  
M. Kumar ◽  
P.J. Bedrossian ◽  
W.E. King
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Thermomechanical Processing ◽  
Electron Backscatter Diffraction ◽  
Grain Boundary Character Distribution ◽  
Atomic Force ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Network Engineering ◽  
Backscatter Diffraction

Grain boundary network engineering is an emerging field that encompasses the concept that modifications to conventional thermomechanical processing can result in improved properties through the disruption of the random grain boundary network. Various researchers have reported a correlation between the grain boundary character distribution (defined as the fractions of “special” and “random” grain boundaries) and dramatic improvements in properties such as corrosion and stress corrosion cracking, creep, etc. While much early work in the field emphasized property improvements, the opportunity now exists to elucidate the underlying materials science of grain boundary network engineering. Recent investigations at LLNL have coupled automated electron backscatter diffraction (EBSD) with transmission electron microscopy (TEM)5 and atomic force microscopy (AFM) to elucidate these fundamental mechanisms.An example of the coupling of TEM and EBSD is given in Figures 1-3. The EBSD image in Figure 1 reveals “segmentation” of boundaries from special to random and random to special and low angle grain boundaries in some grains, but not others, resulting from the 15% compression of an Inconel 600 polycrystal.

Microband-To-Microshear Band Transition near Grain Boundaries in BCC Steel

2007 ◽  
Vol 558-559 ◽  
pp. 873-878 ◽  
Author(s):  
Dorothée Dorner ◽  
Yoshitaka Adachi ◽  
Kaneaki Tsuzaki
Keyword(s):  
Grain Boundary ◽  
Crystal Orientation ◽  
Electron Backscatter Diffraction ◽  
Early Stage ◽  
Compression Tests ◽  
Grain Boundary Characteristics ◽  
Band Transition ◽  
Boundary Characteristics ◽  
Backscatter Diffraction ◽  
Initial Crystal

Compression tests were performed on Fe-3%Si specimens with few grains. The deformation microstructure and microtexture were investigated by electron backscatter diffraction (EBSD) and related to the initial crystal orientation and grain boundary characteristics. Groups of microbands were found that are characterised by a periodic change in crystal orientation, shear at the grain boundary, and the formation of new grains. It is supposed that these microband groups represent an early stage of microshear band development.

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