scholarly journals Microstructure and crystallography of the wall plates of the giant barnacle Austromegabalanus psittacus : a material organized by crystal growth

2020 ◽  
Vol 17 (164) ◽  
pp. 20190743 ◽  
Author(s):  
Antonio G. Checa ◽  
Alicia González-Segura ◽  
Alejandro B. Rodríguez-Navarro ◽  
Nelson A. Lagos
Keyword(s):  
Crystal Morphology ◽  
Electron Backscatter Diffraction ◽  
Construction Materials ◽  
Growth Front ◽  
Growth Surface ◽  
Main Role ◽  
Organic Matrices ◽  
Material Forming ◽  
Backscatter Diffraction

In biomineralization, it is essential to know the microstructural and crystallographic organization of natural hard tissues. This knowledge is virtually absent in the case of barnacles. Here, we have examined the crystal morphology and orientation of the wall plates of the giant barnacle Austromegabalanus psittacus by means of optical and electron microscopy, and electron backscatter diffraction. The wall plates are made of calcite grains, which change in morphology from irregular to rhombohedral, except for the radii and alae, where fibrous calcite is produced. Both the grains and fibres arrange into bundles made of crystallographically co-oriented units, which grow onto each other epitaxially. We call these areas crystallographically coherent regions (CCRs). Each CCR elongates and disposes its c -axis perpendicularly or at a high angle to the growth surfaces, whereas the a -axes of adjacent CCRs differ in orientation. In the absence of obvious organic matrices, this pattern of organization is interpreted to be produced by purely crystallographic processes. In particular, due to crystal competition, CCRs orient their fastest growth axes perpendicular to the growth surface. Since each CCR is an aggregate of grains, the fastest growth axis is that along which crystals stack up more rapidly, that is, the crystallographic c -axis in granular calcite. In summary, the material forming the wall plates of the studied barnacles is under very little biological control and the main role of the mantle cells is to provide the construction materials to the growth front.

A Role of Low Energy Grain Boundaries in the Abnormal Grain Growth in Fe-3%Si Alloy

2011 ◽  
Vol 127 ◽  
pp. 89-94 ◽  
Author(s):  
Ye Chao Zhu ◽  
Jiong Hui Mao ◽  
Fa Tang Tan ◽  
Xue Liang Qiao
Keyword(s):  
Grain Boundaries ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Dominant Role ◽  
Coincidence Site Lattice ◽  
Diffraction Method ◽  
Abnormal Grain Growth ◽  
Low Energy ◽  
Backscatter Diffraction

Low energy grain boundaries were considered to be important in abnormal grain growth by theoretical deduction. The disorientation angles and coincidence site lattice grain boundaries distribution of more than 20 Goss grains and their neighboring matrix grains in primary recrystallized Fe-3%Si alloy were investigated using an electron backscatter diffraction method. It was found that the frequency of low energy grain boundaries of Goss grains which are more likely to abnormally grow are higher than their neighboring matrix grains, which indicated that low energy grain boundaries play a dominant role in the abnormal grain growth of Fe-3%Si alloy. The result meets well with the abnormal grain growth theory.

Numerical and Experimental Investigation on the Hybrid Superplastic Forming of the Conical Mg Alloy Component

2018 ◽  
Vol 385 ◽  
pp. 391-396
Author(s):  
Mei Ling Guo ◽  
Ming Jen Tan ◽  
Xu Song ◽  
Beng Wah Chua
Keyword(s):  
Electron Backscatter Diffraction ◽  
Thickness Distribution ◽  
Superplastic Forming ◽  
Test Results ◽  
Forming Process ◽  
Hyperbolic Sine ◽  
Coarse Grains ◽  
Hot Drawing ◽  
Material Forming ◽  
Backscatter Diffraction

Hybrid superplastic forming (SPF) is a novel sheet metal forming technique that combines hot drawing with gas forming process. Compared with the conventional SPF process, the thickness distribution of AZ31B part formed by this hybrid SPF method has been significantly improved. Additionally, the microstructure evolution of AZ31 was examined by electron backscatter diffraction (EBSD). Many subgrains with low misorientation angle were observed in the coarse grains during SPF. Based on the tensile test results, parameters of hyperbolic sine creep law model was determined at 400 oC. The hybrid SPF behavior of non-superplastic grade AZ31B was predicted by ABAQUS using this material forming model. The FEM results of thickness distribution, thinning characteristics and forming height were compared with the experimental results and have shown reasonable agreement with each other.

scholarly journals Grain Refinement by Extension Twin in Mg Alloy during Asymmetrical Rolling

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 891 ◽  
Author(s):  
I Widiantara ◽  
Hae Yang ◽  
Muhammad Kamil ◽  
Dong Yoon ◽  
Young Ko
Keyword(s):  
Grain Refinement ◽  
Electron Backscatter Diffraction ◽  
Surface Region ◽  
Mg Alloy ◽  
Speed Ratio ◽  
Asymmetrical Rolling ◽  
Present Sample ◽  
Refinement Process ◽  
Backscatter Diffraction

The work looked into the grain refinement process of Mg alloy during asymmetrical rolling with a focus on the role of twin. The present sample was deformed at ambient temperature by single operation with the height reduction of 50% at the roll speed ratio of 1:4 for the upper and lower rolls having the same dimension. From the electron backscatter diffraction analysis in the surface region where intense shear strain was imparted, a number of { 10 1 ¯ 2 } extension twins with a width of ~1 µm were detected clearly in most of the deformed grains. Moreover, the average misorientation angle of the deformed grains in the top region was found to be ~32°, which was two times higher than that in the center area where the extension twin was detected rarely. As a result, the microstructure in the top region was refined significantly down to be ~1.1 µm with an aid of twin activities that would be discussed in this study.

Stabilisation of Aragonite: The Role of Mg2+ and Other Impurity Ions

2019 ◽  
Author(s):  
Matthew Boon ◽  
William Rickard ◽  
Andrew Rohl ◽  
Franca Jones
Keyword(s):  
Electron Backscatter Diffraction ◽  
Crystal Formation ◽  
Sulfate Ions ◽  
Inorganic Systems ◽  
Sodium Magnesium ◽  
Stable Product ◽  
The Stability ◽  
Backscatter Diffraction ◽  
First Time

Aragonite formation and stabilisation in seawater is still an area of active investigation since the thermodynamically stable product at room temperature is calcite. In this manuscript, purely inorganic systems that were found to stabilise aragonite were analysed by various techniques. Dynamic Light Scattering was used to characterise the nucleation behaviour of the system and it was found that the presence of magnesium ions during crystal formation inhibits nucleation overall, not just calcite nucleation. In addition, it was found that sulfate is not necessary to stabilise aragonite. Microanalysis by energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) revealed that the aragonite that was formed had a disordered core with, sodium, magnesium and sulfate ions incorporated into the structure. To the best of the authors’ knowledge this is the first time an ACC core in aragonite has been visualised in a completely abiotic, synthetic system (in the absence of organic molecules). Inclusion of these impurities into the structure may explain the stability of aragonite in natural seawaters.

scholarly journals Quantitative electron microprobe mapping of otoliths suggests elemental incorporation is affected by organic matrices: implications for the interpretation of otolith chemistry

2016 ◽  
Vol 67 (7) ◽  
pp. 889 ◽  
Author(s):  
A. McFadden ◽  
B. Wade ◽  
C. Izzo ◽  
B. M. Gillanders ◽  
C. E. Lenehan ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Electron Backscatter Diffraction ◽  
Growth Patterns ◽  
Otolith Growth ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Organic Matrices ◽  
Plasma Mass Spectrometry ◽  
Minimal Damage ◽  
Backscatter Diffraction

In an effort to understand the mechanism of otolith elemental incorporation, the distribution of strontium (Sr) and sulfur (S) in otoliths of Platycephalus bassensis was investigated in conjunction with otolith growth patterns. Optimisation of electron probe microanalysis (EPMA) quantitative mapping achieved both high spatial resolution (<3µm) and two-dimensional visualisation of the fine scale Sr and S distributions in otoliths of P. bassensis with minimal damage. Electron backscatter diffraction (EBSD) mapping confirmed that grain growth is aligned with the otolith c-axis, with grain orientation independent of both otolith elemental composition and growth patterns. Results showed a linear correlation between Sr and S distribution (R2=0.86), and a clear association with the otolith growth patterns determined by scanning electron microscopy. Further examination by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) showed that incorporation of Mg and Ba appeared independent of both S distribution and the growth patterns. The results suggest that element incorporation into the otolith is linked to the organic composition in the endolymph during mineralisation, and the organic matrices may assist, in part, the uptake of Sr. Thus, these findings may have significant implications for the interpretation of otolith Sr chemistry.

scholarly journals Texture and Shape Analysis of Quartzite Mylonites of the Metamorphic Sole of the Samail Ophiolite (Oman): Evidence for Syn- and Post-Obduction Deformation

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 111
Author(s):  
Peter Hallas ◽  
Wilfried Bauer
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Arabian Plate ◽  
Grain Boundary Migration ◽  
Main Role ◽  
Subgrain Rotation ◽  
Shear Sense ◽  
Subduction System ◽  
Backscatter Diffraction

The metamorphic sole, tectonically welded to the base of the Samail ophiolite in a supra-subduction system, is assumed to play the main role in strain accumulation during later thrusting onto the Arabian Plate (i.e., during obduction). The present study deals with five quartzite samples representative of the upper amphibolite and lower greenschist facies parts of the sole. Whole-rock textures obtained by neutron time-of-flight technique were coupled with microstructural observation using electron backscatter diffraction analyses. The quartz microstructural fabrics and textures in the upper and lower parts of the sole represent grain boundary migration and [c]-in-Y textures and subgrain rotation recrystallization and {r}-in-Z textures, respectively. The shear sense in these samples points to top-to-the-SW to SSW shear. One sample of the upper part, yielding a higher calcite amount, is later overprinted by bulging and displays top-to-the-NNE shear. We postulate to differentiate two main deformation steps. The first is the overall present subgrain rotation and grain boundary migration recrystallization combined to top ~SW shear is related to the sole accretion to the ophiolite and the eventually following thrusting onto the Arabian Plate. The second is correlated to a post-obduction extensional top-to-the-NNE shearing, which is associated with tectonic thinning of the ophiolite and mainly documented in the underlying autochthonous units.

scholarly journals Deformation compatibility in a single crystalline Ni superalloy

2016 ◽  
Vol 472 (2185) ◽  
pp. 20150690 ◽  
Author(s):  
Jun Jiang ◽  
Tiantian Zhang ◽  
Fionn P. E. Dunne ◽  
T. Ben Britton
Keyword(s):  
Electron Backscatter Diffraction ◽  
Deformation Gradient ◽  
Advanced Characterization ◽  
Image Correlation ◽  
Polycrystalline Materials ◽  
High Angular Resolution ◽  
Resolution Electron ◽  
Backscatter Diffraction ◽  
Deformation Gradients

Deformation in materials is often complex and requires rigorous understanding to predict engineering component lifetime. Experimental understanding of deformation requires utilization of advanced characterization techniques, such as high spatial resolution digital image correlation (HR-DIC) and high angular resolution electron backscatter diffraction (HR-EBSD), combined with clear interpretation of their results to understand how a material has deformed. In this study, we use HR-DIC and HR-EBSD to explore the mechanical behaviour of a single-crystal nickel alloy and to highlight opportunities to understand the complete deformations state in materials. Coupling of HR-DIC and HR-EBSD enables us to precisely focus on the extent which we can access the deformation gradient, F , in its entirety and uncouple contributions from elastic deformation gradients, slip and rigid body rotations. Our results show a clear demonstration of the capabilities of these techniques, found within our experimental toolbox, to underpin fundamental mechanistic studies of deformation in polycrystalline materials and the role of microstructure.

scholarly journals Microstructure Evolution During Hot Deformation of REX734 Austenitic Stainless Steel

2019 ◽  
Vol 51 (2) ◽  
pp. 845-854 ◽  
Author(s):  
Mykola Kulakov ◽  
Jianglin Huang ◽  
Michail Ntovas ◽  
Shanmukha Moturu
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Electron Backscatter Diffraction ◽  
Compression Testing ◽  
Recrystallization Process ◽  
Twin Boundaries ◽  
Wide Range ◽  
Evolution Of Microstructure ◽  
Backscatter Diffraction

AbstractMechanical properties of a REX734 austenitic stainless steel were examined through compression testing over a wide range of temperatures (1173 K to 1373 K (900 °C to 1100 °C)) and strain rates (0.1 to 40 s−1) that cover deformation conditions encountered in different metalworking processes. The evolution of microstructure was studied using electron microscopy combined with electron backscatter diffraction and energy-dispersive spectroscopy. Partially recrystallized microstructures were obtained after compression testing at 1173 K (900 °C), while after deformation at 1273 K and 1373 K (1000 °C and 1100 °C), the material was fully recrystallized almost in all examined cases. The role of dynamic and metadynamic restoration processes in the formation of final microstructure was investigated. Σ3 twin boundaries lost their twin character and transformed into general high-angle grain boundaries as a result of deformation, while during recrystallization new Σ3 twin boundaries formed. The evolution of precipitates during compression testing and their role in the recrystallization process was also discussed.

Role of Texture in Understanding Creep Flow in HPT-Processed Ultrafine Grained Copper

2011 ◽  
Vol 702-703 ◽  
pp. 370-373
Author(s):  
Jörn Leuthold ◽  
Matthias Wegner ◽  
Sergiy V. Divinski ◽  
K. Anantha Padmanabhan ◽  
Daria Setman ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
Tensile Elongation ◽  
Tensile Creep ◽  
Creep Flow ◽  
Ultrafine Grained ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Disks of copper samples were produced by High Pressure Torsion (HPT). Specimens for tensile creep experiments were cut from the disks and subjected to creep deformation at 348 K to obtain elongations greater than 30%. Electron backscatter diffraction (EBSD) was used to analyze the texture after HPT deformation and after additional tensile elongation.

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