Dynamic Recrystallisation of Quartz

2004 ◽  
Vol 467-470 ◽  
pp. 1243-1250 ◽  
Author(s):  
John Wheeler ◽  
Zhenting Jiang ◽  
David J. Prior ◽  
Jan Tullis
Keyword(s):  
Driving Force ◽  
Strain Energy ◽  
Electron Backscatter Diffraction ◽  
Dislocation Creep ◽  
High Angle ◽  
Subgrain Rotation ◽  
Electron Backscatter ◽  
Dynamic Recrystallisation ◽  
Plastic Strain Energy ◽  
Backscatter Diffraction

It is generally agreed that the driving force (plastic strain energy) is much too small to allow "classical" nucleation during static and dynamic recrystallisation, and that rotation/growth of subgrains is an alternative. The latter explanation predicts that new grains should begin at low angles to old grains. We have used electron backscatter diffraction on an experimentally deformed quartz polycrystal that has deformed by dislocation creep and partially recrystallised. In a region shortened by about 30% new grains are at high angles (much greater than 15º) to adjacent parent grains. A histogram of misorientation versus number of boundaries shows a gap at 15-20º. In its simple form we expect the subgrain rotation model to predict a spectrum of misorientations but with most of them being low angle. Instead, the histogram suggests that new boundaries began life as high-angle structures, so current models for deformation-induced nucleation require refinement.

scholarly journals Analysis of Strain Partitioning in Intercritically Deformed Microstructures via Interrupted Tensile Tests

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Unai Mayo ◽  
Nerea Isasti ◽  
José M. Rodríguez-Ibabe ◽  
Pello Uranga
Keyword(s):  
Electron Backscatter Diffraction ◽  
Tensile Tests ◽  
Correlation Technique ◽  
Strain Partitioning ◽  
High Angle ◽  
Electron Backscatter ◽  
Different Types ◽  
Final Deformation ◽  
Micro Alloyed Steel ◽  
Backscatter Diffraction

Intercritically deformed steels present combinations of different types of ferrite, such as deformed ferrite (DF) and non-deformed ferrite (NDF) grains, which are transformed during the final deformation passes and final cooling step. Recently, a grain identification and correlation technique based on EBSD has been employed together with a discretization methodology, enabling a distinction to be drawn between different ferrite populations (NDF and DF grains). This paper presents a combination of interrupted tensile tests with crystallographic characterization performed by means of Electron Backscatter Diffraction (EBSD), by analyzing the evolution of an intercritically deformed micro-alloyed steel. In addition to this, and using the nanoindentation technique, both ferrite families were characterized micromechanically and the nanohardness was quantified for each population. NDF grains are softer than DF ones, which is related to the presence of a lower fraction of low-angle grain boundaries. The interrupted tensile tests show the different behavior of low- and high-angle grain boundary evolution as well as the strain partitioning in each ferrite family. NDF population accommodates most of the deformation at initial strain intervals, since strain reaches 10%. For higher strains, NDF and DF grains behave similarly to the strain applied.

scholarly journals Dislocation Creep of Olivine and Amphibole in Amphibole Peridotites from Åheim, Norway

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1018
Author(s):  
Sejin Jung ◽  
Takafumi Yamamoto ◽  
Jun-ichi Ando ◽  
Haemyeong Jung
Keyword(s):  
Electron Microscopy ◽  
Slip System ◽  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Dislocation Creep ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Different Types ◽  
Localized Shear Deformation ◽  
Backscatter Diffraction

Amphibole peridotite samples from Åheim, Norway, were analyzed to understand the deformation mechanism and microstructural evolution of olivine and amphibole through the Scandian Orogeny and subsequent exhumation process. Three Åheim amphibole peridotite samples were selected for detailed microstructural analysis. The Åheim amphibole peridotites exhibit porphyroclastic texture, abundant subgrain boundaries in olivine, and the evidence of localized shear deformation in the tremolite-rich layer. Two different types of olivine lattice preferred orientations (LPOs) were observed: B- and A-type LPOs. Electron backscatter diffraction (EBSD) mapping and transmission electron microscopy (TEM) observations revealed that most subgrain boundaries in olivine consist of dislocations with a (001)[100] slip system. The subgrain boundaries in olivine may have resulted from the deformation of olivine with moderate water content. In addition, TEM observations using a thickness-fringe method showed that the free dislocations of olivine with the (010)[100] slip system were dominant in the peridotites. Our data suggest that the subgrain boundaries and free dislocations in olivine represent a product of later-stage deformation associated with the exhumation process. EBSD mapping of the tremolite-rich layer revealed intracrystalline plasticity in amphibole, which can be interpreted as the activation of the (100)[001] slip system.

scholarly journals Forming Mechanism of High-Speed Cold Roll Beating of Spline Tooth

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Ting Niu ◽  
Yong-Tang Li ◽  
Zhi-Qi Liu ◽  
Hui-Ping Qi
Keyword(s):  
Process Parameters ◽  
High Speed ◽  
Room Temperature ◽  
Electron Backscatter Diffraction ◽  
Forming Mechanism ◽  
Grain Sizes ◽  
Cold Roll ◽  
Subgrain Rotation ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The spline tooth of ASTM 1045 was fabricated by high-speed cold roll-beating (HSCRB) process at room temperature. Microhardness of the spline tooth was examined by a nanoindenter. The grains and misorientation angle distributions were measured by electron backscatter diffraction (EBSD). The results showed that the microhardness was improved up to 1280 μm deep from the surface of the spine tooth. The microhardness and the grain sizes gradually decreased in the direction away from the surface. On the surface, the fraction of ultrafine grains increased up to about 90%, and the average grain diameter (which was ∼0.56 µm) decreased by 71.4%. The model of grain evolution during HSCRB process is proposed in this work. New grains appear first on the boundaries of the elongated grains within numerous subgrains. The elongated grains are refined as a result of subgrain rotation. By analyzing the HSCRB technical principle, we concluded that the process parameters affect the refinement degree of studied steel by determining beating pass, beating pass interval time, and strain rate.

Electron Backscatter Diffraction-Enabled Anisotropic Thermo-Elastic Analysis of Additively Manufactured Single Tracks

2019 ◽  
Author(s):  
Andrew J. Birnbaum ◽  
John G. Michopoulos ◽  
John C. Steuben ◽  
Athanasios P. Iliopoulos
Keyword(s):  
Strain Energy ◽  
Electron Backscatter Diffraction ◽  
Energy State ◽  
Large Body ◽  
Elastic Strain Energy ◽  
Initial Step ◽  
Structural Features ◽  
Shear Stresses ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract Despite extensive efforts directed toward elucidating the connections between process, microstructure and performance of additively manufactured structures and components, a significant number of meaningful questions remain unanswered. Specifically, a large body of work has demonstrated that microstructural/sub-structural features in selectively laser melted (SLM) components give rise to a significant enhancement in strength. Furthermore, the change in associated ductility is comparable to that seen in post-processed, wrought annealed material. However, the origin and mechanism by which these features arise have remained elusive. This work is an initial step in leveraging computational capabilities for validating experiment-based theories that explain the basis for the above-mentioned phenomena. The present work describes a computational approach for utilizing spatially resolved crystal-lographic descriptions obtained via electron backscatter diffraction (EBSD) to define the domain geometry and material properties of an anisotropic thermo-elastic simulation. The resulting solution is used to ascertain the elastic strain energy state, and slip-system resolved shear stresses on a per-grain basis. This analysis is performed, in part, as a means for validating a hypothesis linking these characteristics with the development of sub-structural features, which are in turn, correlated with improvements in material performance. The results suggest that both strain energy density and grain boundary character play an important role in the formation of substructure in additively manufactured 316L stainless steels.

The Crystallography of Pyrite Framboids

2021 ◽  
pp. 110-128
Author(s):  
David Rickard
Keyword(s):  
Single Crystal ◽  
Driving Force ◽  
Structural Control ◽  
Electron Backscatter Diffraction ◽  
X Ray Diffraction ◽  
Entropy Maximization ◽  
Self Organized ◽  
Electron Backscatter ◽  
Ordered Array ◽  
Backscatter Diffraction

Single crystal X-ray diffraction analyses of even the most perfectly organized framboids show ring patterns indicative of randomly oriented particles. Therefore, framboids are not mesocrystals or extreme skeletal varieties of single crystals. Electron backscatter diffraction shows that the microcrystals within a framboid are not crystallographically aligned. Around half of the microcrystals in organized framboids have crystallographic orientations rotated 90º. The results of single crystal XRD and framboid EBSD studies clearly show that the microcrystals are self-organized rather than being the result of a crystallographic template or preexisting structural control. The pre-formed framboid microcrystals which are initially randomly organized throughout the framboid volume then, in some cases, begin to wholly or partly self-order. This is effected by rotation of the microcrystals until an ordered array is produced. The consequence of this rotation must be that the microcrystals are initially packed loosely enough for rotation to occur. The processes involved in the rotation could include forces intrinsic to the microcrystals themselves, such as surface forces, or forces imposed from outside the framboid, such as Brownian motion. The fundamental driving force for microcrystal rotation and the development of organized microcrystal arrays in framboids is entropy maximization.

Orientation transformation of Pb grains in 5Sn–95Pb/ 63Sn–37Pb composite flip-chip solder joints during electromigration test

2008 ◽  
Vol 23 (7) ◽  
pp. 1877-1881 ◽  
Author(s):  
Ying-Ta Chiu ◽  
Kwang-Lung Lin ◽  
Yi-Shao Lai
Keyword(s):  
Electron Microscopy ◽  
Driving Force ◽  
Flip Chip ◽  
Solder Bump ◽  
Solder Joints ◽  
Electron Backscatter Diffraction ◽  
Current Stressing ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Scanning Electron

Microstructural evolution occurred in 5Sn–95Pb/63Sn–37Pb composite flip-chip solder bump during electromigration. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations for 5Sn–95Pb/63Sn–37Pb composite flip-chip solder joints subjected to 5 kA/cm2 current stressing at 150 °C revealed a gradual orientation transformation of Pb grains from random textures toward (101) grains. We proposed that the combination of reducing the surface energy of Pb grain boundaries and resistance of the entire polycrystalline system are the driving force for the orientation transformation of Pb grains during an electromigration test.

Nucleation and Texture Development during Dynamic Recrystallization of Copper

2005 ◽  
Vol 495-497 ◽  
pp. 1195-1200 ◽  
Author(s):  
D.T. McDonald ◽  
John F. Humphreys ◽  
Pete S. Bate
Keyword(s):  
Dynamic Recrystallization ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Deformation Texture ◽  
Texture Development ◽  
Polycrystalline Copper ◽  
High Angle ◽  
Resolution Electron ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Dynamic recrystallization and texture development in polycrystalline copper have been investigated. Specimens were deformed in channel-die plane strain compression to true strains from 0.1 to 0.7 within the temperature range 200°C to 600°C, and the resulting microstructures were investigated with the use of high resolution electron backscatter diffraction (EBSD). Dynamic recrystallization in copper was initiated by the bulging of pre-existing high angle grain boundaries (HAGB), and occurred primarily by strain induced boundary migration (SIBM). Increasing misorientations from parent to dynamically recrystallizing grains indicated the occurrence of lattice rotations within the bulges, leading, in some cases to the formation of a HAGB behind the bulge. Discrimination between recrystallized and deformed components in material which had partially undergone dynamic recrystallization was carried out, followed by texture analysis. This revealed most of the recrystallized material to have orientations close to that of the deformed material, however, some remote orientations were observed which could not be related to the deformation texture by twin or 40° <111> relationships.

Using Electron Backscatter Diffraction (EBSD) to Measure Misorientation between ‘Parent’ and ‘Daughter’ Grains. Implications for Recrystallisation and Nucleation

2004 ◽  
Vol 467-470 ◽  
pp. 573-578 ◽  
Author(s):  
Angela Halfpenny ◽  
David J. Prior ◽  
John Wheeler
Keyword(s):  
Crystallographic Orientation ◽  
Electron Backscatter Diffraction ◽  
Mantle Structure ◽  
Boundary Misorientation ◽  
Original Parent ◽  
Subgrain Rotation ◽  
Electron Backscatter ◽  
Orientation Information ◽  
Backscatter Diffraction

Electron backscatter diffraction (EBSD) is an extremely valuable tool, as it measures full crystallographic orientation information. This technique has been used to measure the statistics of misorientations between original ‘parent’ grains and recrystallised ‘daughter’ grains in a mylonitic quartzite. The angle of misorientation has implications on the controlling recrystallisation mechanism. The sample is a natural mylonitic quartzite collected from the stack of Glencoul, NW Scotland. The sample exhibits a common partially recrystallised microstructure. The data shows the average misorientations between the ‘parent’ and ‘daughter’ grains are 30º, this value seems too high for only subgrain rotation recrystallisation to be taking place. Moreover there is no gradation in the boundary misorientation from the internal substructure of the ‘parent’ grain to the ‘daughter’ grains. The internal substructure size of the ‘parent’ grain is bigger than the size of the ‘daughter’ grains. For subgrain rotation recrystallisation you may expect to see a core and mantle structure and for the ‘daughter’ grains’ to be of similar size to the internal substructure of the ‘parent’ grain. Another mechanism has either controlled the recrystallisation altogether or has become active after subgrain rotation had taken place and modified the microstructure.

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