scholarly journals Microstructure and Texture Evolutions During Deep Drawing of Mg–Al–Mn Sheets at Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3608 ◽  
Author(s):  
Jae-Hyung Cho ◽  
Sang-Ho Han ◽  
Geon Young Lee
Keyword(s):  
Dynamic Recrystallization ◽  
Deep Drawing ◽  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Grain Structure ◽  
Transmission Electron ◽  
Backscatter Diffraction ◽  
Twin Roll

Texture and microstructure evolution of ingot and twin-roll casted Mg–Al–Mn magnesium sheets were examined during deep drawing at elevated temperatures. The twin-roll casted sheets possessed smaller grain sizes and weaker basal intensity levels than the ingot-casted sheets. The strength and elongation at room temperature for the twin-roll casted sheets were greater than those of the ingot-casted sheets. At elevated temperatures, the ingot-casted sheets showed better elongation than the twin-roll casted sheets. Different size and density of precipitates were examined using transmission electron microscopy (TEM) for both ingot-casted and twin-roll-casted sheets. The deep drawing process was also carried out at various working temperatures and deformation rates, 225 °C to 350 °C and 30 mm/min to 50 mm/min, respectively. The middle wall part of cups were mainly tensile deformation, and the lower bent regions of drawn cups were most thinned region. Overall, the ingot-casted sheets revealed better deep drawability than the twin-roll casted sheets. Microstructure and texture evolution of the top, middle and lower parts of drawn cups were investigated using electron backscatter diffraction. Increased deformation rate is important to activate tensile twins both near the bent and flange areas. Ingot casted sheets revealed more tensile twins than twin-roll casted sheets. Increased working temperature is important to activate non-basal slips and produce the DRXed grain structure in the flange. Dynamic recrystallization were frequently found in the top flanges of the cups. Both tensile twins and non-basal slips contributed to occurrence of the dynamic recrystallization in the flange.

scholarly journals Investigation on Sub-Solvus Recrystallization Mechanisms in an Advanced γ-γ’ Nickel-Based Superalloy GH4151

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4553
Author(s):  
Shaomin Lv ◽  
Jinbin Chen ◽  
Xinbo He ◽  
Chonglin Jia ◽  
Kang Wei ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Energy Surface ◽  
Electron Backscatter Diffraction ◽  
True Strain ◽  
Continuous Dynamic Recrystallization ◽  
Nickel Based Superalloy ◽  
Transmission Electron ◽  
Continuous Dynamic ◽  
Backscatter Diffraction

Sub-solvus dynamic recrystallization (DRX) mechanisms in an advanced γ-γ’ nickel-based superalloy GH4151 were investigated by isothermal compression experiments at 1040 °C with a strain rate of 0.1 s−1 and various true strain of 0.1, 0.3, 0.5, and 0.7, respectively. This has not been reported in literature before. The electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) technology were used for the observation of microstructure evolution and the confirmation of DRX mechanisms. The results indicate that a new dynamic recrystallization mechanism occurs during hot deformation of the hot-extruded GH4151 alloy. The nucleation mechanism can be described as such a feature, that is a primary γ’ (Ni3(Al, Ti, Nb)) precipitate embedded in a recrystallized grain existed the same crystallographic orientation, which is defined as heteroepitaxial dynamic recrystallization (HDRX). Meanwhile, the conventional DRX mechanisms, such as the discontinuous dynamic recrystallization (DDRX) characterized by bulging grain boundary and continuous dynamic recrystallization (CDRX) operated through progressive sub-grain merging and rotation, also take place during the hot deformation of the hot-extruded GH4151 alloy. In addition, the step-shaped structures can be observed at grain boundaries, which ensure the low-energy surface state during the DRX process.

Formation of Nanoporous Gold Studied by Transmission Electron Backscatter Diffraction

2015 ◽  
Vol 21 (6) ◽  
pp. 1387-1397 ◽  
Author(s):  
Leo T.H. de Jeer ◽  
Diego Ribas Gomes ◽  
Jorrit E. Nijholt ◽  
Rik van Bremen ◽  
Václav Ocelík ◽  
...  
Keyword(s):  
Crystallographic Texture ◽  
Manufacturing Process ◽  
Electron Backscatter Diffraction ◽  
Nanoporous Materials ◽  
Nanoporous Gold ◽  
Grain Structure ◽  
Misorientation Distribution ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Backscatter Diffraction

AbstractTransmission electron backscatter diffraction (t-EBSD) was used to investigate the effect of dealloying on the microstructure of 140-nm thin gold foils. Statistical and local comparisons of the microstructure between the nonetched and nanoporous gold foils were made. Analyses of crystallographic texture, misorientation distribution, and grain structure clearly prove that during the dealloying manufacturing process of nanoporous materials the crystallographic texture is enhanced significantly with a clear decrease of internal strain, whereas maintaining the grain structure.

scholarly journals Cryogenic Deformation Behavior and Microstructural Characteristics of 2195 Alloy

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1406
Author(s):  
Jin Zhang ◽  
Wenfu Tan ◽  
Cheng Wang ◽  
Chunnan Zhu ◽  
Youping Yi
Keyword(s):  
Electron Microscope ◽  
Electron Backscatter Diffraction ◽  
Underlying Mechanism ◽  
Optical Microscope ◽  
W State ◽  
Grain Structure ◽  
Cryogenic Deformation ◽  
Transmission Electron ◽  
Strength And Plasticity ◽  
Backscatter Diffraction

Cryogenic deformation can improve the strength and plasticity of Al–Li alloy, although the underlying mechanism is still not yet well understood. The effects of cryogenic temperature on the tensile properties and microstructure of an Al–Cu–Li alloy were investigated by means of tensile property test, roughness measurement, scanning electron microscope (SEM), optical microscope (OM), electron backscatter diffraction (EBSD), and transmission electron microscope (TEM). The results indicated that the strength and elongation of the as-annealed (O-state) and solution-treated (W-state) alloys increased with the decrease in deformation temperature, where the increasing trend of elongation of the W-state alloy was more significant than that of the O-state alloy. In addition, a temperature range was observed at approximately 178 K that caused the strength of the W-state alloy to slightly decrease. The decrease in temperature inhibited the dynamic recovery of the Al–Cu–Li alloy, which increased the dislocation density and the degree of work hardening, thus improving the strength of the alloy. At cryogenic temperatures, the internal grain structure was more involved in the deformation and the overall deformation was more uniform, which caused the alloy to have higher plasticity. This study provides a theoretical basis for the cryogenic forming of Al–Li alloy.

Static Recrystallization of Magnesium Alloy during TRC-HC Deformation Followed by Annealing

2011 ◽  
Vol 295-297 ◽  
pp. 730-733 ◽  
Author(s):  
Yong Wang ◽  
Shou Ren Wang ◽  
Ru Ma ◽  
Li Ying Yang
Keyword(s):  
Magnesium Alloy ◽  
Grain Boundary ◽  
Static Recrystallization ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Transmission Electron ◽  
Subgrain Rotation ◽  
Twin Roll Cast ◽  
Backscatter Diffraction ◽  
Twin Roll

Using optical microscopy, electron backscatter diffraction and transmission electron microscopy, the static recrystallization (SRX) mechanisms of ZK 60 magnesium alloy was examined under twin-roll-cast and hot compression (TRC-HC, 350 °C/0.1 s-1) and subsequent annealing (1000 second at 250-400°C). The static recrystallization (SRX) mechanisms, such as grain boundary migration (GBM), grain boundary bulging (GLB) and subgrain rotation (SGR), were discussed.

High-temperature oxidation of CoGa: Influence of the crystallographic orientation on the oxidation rate

2002 ◽  
Vol 17 (10) ◽  
pp. 2489-2498 ◽  
Author(s):  
U. Koops ◽  
D. Hesse ◽  
M. Martin
Keyword(s):  
High Temperature ◽  
Crystallographic Orientation ◽  
High Temperature Oxidation ◽  
Elevated Temperatures ◽  
Electron Backscatter Diffraction ◽  
Ex Situ ◽  
Temperature Oxidation ◽  
Transmission Electron ◽  
Backscatter Diffraction

The crystallographic orientation plays an important role in high-temperature oxidation of the intermetallic compound CoGa. When CoGa is exposed to air at elevated temperatures, the oxide β–Ga2O3 is formed, and different scale growth rates are observed, depending on the crystallographic orientation of the CoGa grains. This dependence is a consequence of the anisotropy of the gallium diffusion rate through the β–Ga2O3 scale and of a topotaxial orientation relationship occurring between β–Ga2O3 and CoGa. The combination of ex situ techniques, such as transmission electron microscopy and electron backscatter diffraction with optical microscopy, applied in situ resulted in a thorough understanding of these relations and of the oxidation process in general.

Deep Drawing of ZK60 Wrought Magnesium Alloys

2011 ◽  
Vol 702-703 ◽  
pp. 48-51
Author(s):  
Jae Hyung Cho ◽  
Sang Su Jeong ◽  
Suk Bong Kang
Keyword(s):  
Magnesium Alloys ◽  
Deep Drawing ◽  
Working Condition ◽  
Electron Backscatter Diffraction ◽  
Direct Chill ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Working Temperature ◽  
Backscatter Diffraction ◽  
Twin Roll

Evolution of texture and microstructure during deep drawing of ZK60 wrought magnesium alloys were investigated using EBSD (electron backscatter diffraction). ZK60 (Mg-5.5Zn-0.6Zr) alloys were prepared through both direct chill casting (DC) and twin-roll strip casting (TRC). Deep drawing tests were carried out under various working temperature and drawing speeds. The diameters of the sheets and punch were 74 mm and 37 mm, and overall limit drawing ratio was 2. Texture and microstructure evolution was examined with various working condition. The DC samples had larger grains than TRC samples, and thus more twins were observed in the DC samples.

scholarly journals Effect of Dynamic Recrystallization on the Transformed Ferrite Microstructures in HSLA Steel

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 817 ◽  
Author(s):  
Ning Li ◽  
Wilasinee Kingkam ◽  
Renheng Han ◽  
Ming Tang ◽  
Hexin Zhang ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Hsla Steel ◽  
True Strain ◽  
High Strength ◽  
Transmission Electron ◽  
High Fraction ◽  
Backscatter Diffraction

The flow stress behavior of high-strength low-alloy (HSLA) steel at different true strains was studied using a hot compression test. The effect of dynamic recrystallization (DRX) on the transformed ferrite microstructures was investigated with electron backscatter diffraction (EBSD). The EBSD analysis indicated that the fraction of high-angle grain boundaries (HAGBs) and DRX increased with increasing true strain. The low-angle grain boundaries (LAGBs) were gradually transformed into HAGBs with increasing DRX degree. When the true strain was increased to 0.916, the fraction of HAGBs increased to 85% and the fraction of DRX increased to 80.3%. The relatively high fraction of HAGBs was related to the complete DRX. The dislocations and substructures in the tested steel at different true strains were characterized by transmission electron microscopy (TEM). TEM observation shows that the nucleation of the dynamically recrystallized grains occurred by the bulging of the original grain boundaries. The DRX nucleation mechanism of the HSLA steel is the strain-induced grain boundary migration mechanism.

Accumulative Roll-Bonding (ARB) of Sheets of Aluminium and its Commercial Alloys AA8006 and AA5754 at Ambient and Elevated Temperatures

2007 ◽  
Vol 546-549 ◽  
pp. 767-774 ◽  
Author(s):  
Miroslav Karlík ◽  
Margarita Slámová ◽  
Petr Homola ◽  
P. Sláma ◽  
Miroslav Cieslar
Keyword(s):  
Elevated Temperatures ◽  
Large Fraction ◽  
True Strain ◽  
Grain Structure ◽  
Pure Aluminium ◽  
High Concentration ◽  
Fine Grain ◽  
Transmission Electron ◽  
Twin Roll Cast ◽  
Twin Roll

Mechanical properties and microstructure of twin-roll cast (TRC) pure aluminium, Al-Fe-Mn-Si (AA8006) and Al-Mg (AA5754) alloy sheets ARB processed at ambient and elevated temperatures (200, 250, 300 and 350°C) were investigated. Processing at elevated temperatures results in better bonding but it produces smaller increases in hardness. AA8006 specimens were processed without any problems up to 7 cycles. The alloy AA5754 suffered from severe edge and notch cracking since the first cycle. The strength was evaluated from tensile test and microhardness measurements; the microstructure was examined using light microscopy, and transmission electron microscopy. The microstructure was compared to that of conventionally cold rolled (CCR) specimens with true strain ε of 0.8, 1.6, 2.4 and 3.2 corresponding to the strain induced by 1 to 4 ARB cycles. The work hardening of alloy AA8006 saturated after the 3rd cycle, whereas the hardness of alloy AA5754 increased steadily up to the 5th cycle. Very fine grain structure with large fraction of high angle boundaries was observed in both alloys after two cycles of ARB. The grains were refined to submicrometre and nanometre size (down to 90 nm in alloy AA5754). Intensive post-dynamic recovery was observed in AA8006 specimens. The recovery is less pronounced in the AA5754 alloy with high concentration of solute atoms in solid solution.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

Where are the geometrically necessary dislocations accommodating small imprints?

2009 ◽  
Vol 24 (3) ◽  
pp. 647-651 ◽  
Author(s):  
M. Rester ◽  
C. Motz ◽  
R. Pippan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Twin Boundary ◽  
Crystal Orientation ◽  
Electron Backscatter Diffraction ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Copper Single Crystals ◽  
Backscatter Diffraction ◽  
Small Misorientation

Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses of small indentations in copper single crystals exhibit only slight changes of the crystal orientation in the surroundings of the imprints. Far-reaching dislocations might be the reason for these small misorientation changes. Using EBSD and TEM technique, this work makes an attempt to visualize the far-propagating dislocations by introducing a twin boundary in the vicinity of small indentations. Because dislocations piled up at the twin boundary produce a misorientation gradient, the otherwise far-propagating dislocations can be detected.

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