Cryogenic Deformation Behavior and Microstructural Characteristics of 2195 Alloy

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.

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

Materials ◽

10.3390/ma13163608 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3608 ◽

Cited By ~ 1

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.

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Reduced Unit Cell Determination From Unindexed EBSD Patterns

Microscopy and Microanalysis ◽

10.1017/s1431927600037223 ◽

2000 ◽

Vol 6 (S2) ◽

pp. 946-947 ◽

Cited By ~ 1

Author(s):

J. R. Michael ◽

R. P. Goehner

Keyword(s):

Electron Microscope ◽

Electron Backscatter Diffraction ◽

Unit Cell ◽

Phase Identification ◽

High Quality ◽

Charge Coupled Device ◽

Transmission Electron ◽

Single Pattern ◽

Backscatter Diffraction

Electron backscatter diffraction (EBSD) is a technique that can provide identification of unknown crystalline phases while exploiting the excellent imaging capabilities of the scanning electron microscope (SEM). Phase identification using EBSD has now progressed to the point that it is commercially available. Phase identification in the SEM requires high quality EBSD patterns that can only be collected using either film or charge coupled device (CCD)-based cameras. High quality EBSD patterns obtained in this manner show many diffraction features that are useful in the determination of the unit cell of the sample.’ This paper will discuss the features in the EBSD patterns and the procedure used to determine the reduced unit cell of the sample.One of the major advantages of EBSD over electron diffraction in the transmission electron microscope is the remarkable field of view that is routinely attained. The large angular view of the diffraction pattern permits many zone axes and their associated symmetries to be viewed in a single pattern or at most a few patterns.

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Microstructure Evolution and Mechanical Property Characterization of 6063 Aluminum Alloy Tubes Processed with Friction Stir Back Extrusion

JOM ◽

10.1007/s11837-019-03852-7 ◽

2019 ◽

Vol 71 (12) ◽

pp. 4436-4444

Author(s):

Suhong Zhang ◽

Alan Frederick ◽

Yiyu Wang ◽

Mike Eller ◽

Paul McGinn ◽

...

Keyword(s):

Aluminum Alloy ◽

Microstructure Evolution ◽

Electron Backscatter Diffraction ◽

Deformation Gradient ◽

Optical Microscope ◽

Grain Structure ◽

Frictional Heat ◽

Friction Stir ◽

Metal Extrusion ◽

Backscatter Diffraction

Abstract Friction stir back extrusion (FSBE) is a technique for lightweight metal extrusion. The frictional heat and severe plastic deformation of the process generate an equiaxed refined grain structure because of dynamic recrystallization. Previous studies proved that the fabrication of tube and wire structures is feasible. In this work, hollow cylindrical billets of 6063-T6 aluminum alloy were used as starting material. A relatively low extrusion ratio allows for a temperature and deformation gradient through the tube wall thickness to elucidate the effect of heat and temperature on the microstructure evolution during FSBE. The force and temperature were recorded during the processes. The microstructures of the extruded tubes were characterized using an optical microscope, energy-dispersive x-ray spectroscopy, electron backscatter diffraction, and hardness testing. The process reduced the grain size from 58.2 μm to 20.6 μm at the inner wall. The microhardness of the alloy was reduced from 100 to 60–75 HV because of the process thermal cycle.

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Comparison of Grain Structures and Textures in AA5754 Aluminum Alloy Sheets Processed by Room Temperature Rolling and Rolling with Liquid Nitrogen

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.217 ◽

2007 ◽

Vol 558-559 ◽

pp. 217-222 ◽

Cited By ~ 1

Author(s):

Hai Ou Jin ◽

Pei Dong Wu ◽

David J. Lloyd

Keyword(s):

Liquid Nitrogen ◽

Room Temperature ◽

Electron Backscatter Diffraction ◽

Optical Microscope ◽

Grain Structure ◽

Micro Hardness ◽

Grain Structures ◽

Room Temperature Rolling ◽

The One ◽

Backscatter Diffraction

Two AA5754 sheets have been processed by cold rolling with 83% thickness reduction, one at room temperature and another with liquid nitrogen as coolant. The sheets were subsequently annealed at 220-275°C for 1 hour. The development of grain structure and texture was studied by optical microscope, scanning electron microscopy (SEM), X-ray diffraction and electron backscatter diffraction (EBSD) in SEM, and the mechanical property by micro-hardness testing. It has been demonstrated that the as-rolled sheets have the same micro-hardness, but the grain structures and textures are very different. Compared to the sheet processed with liquid nitrogen, the one rolled at room temperature has stronger shear texture and finer grain structure.

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Formation of Nanoporous Gold Studied by Transmission Electron Backscatter Diffraction

Microscopy and Microanalysis ◽

10.1017/s1431927615015329 ◽

2015 ◽

Vol 21 (6) ◽

pp. 1387-1397 ◽

Cited By ~ 3

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.

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Characterization of the Interface Between α and β Titanium Alloys in the Diffusion Couple

Metallurgical and Materials Transactions A ◽

10.1007/s11661-020-06023-5 ◽

2020 ◽

Vol 51 (12) ◽

pp. 6584-6591

Author(s):

Maciej Motyka ◽

Wojciech J. Nowak ◽

Bartek Wierzba ◽

Witold Chrominski

Keyword(s):

Electron Microscope ◽

Diffusion Couple ◽

Titanium Alloys ◽

Solid Solutions ◽

Electron Backscatter Diffraction ◽

Inert Atmosphere ◽

Microstructural Changes ◽

Transmission Electron ◽

Titanium Grade ◽

Backscatter Diffraction

AbstractThe aim of the research was to investigate the microstructural changes caused by diffusion through interface between α and β titanium solid solutions. For this purpose, a diffusion couple composed of two single-phase titanium alloys—α type commercially pure (CP) titanium Grade 2 and near-β Ti-15V-3Al-3Cr-3Sn—was made by annealing at a temperature of 850 °C in an inert atmosphere. The performed heat treatment caused partial diffusion bonding (DB) where the α/β-interface was clearly visible. Based on the results of microscopic (light microscope (LM), scanning electron microscope/electron backscatter diffraction (SEM/EBSD), and transmission electron microscope (TEM)) examination, a significant microstructure evolution of near-β alloy in the region near the interface (diffusion-affected zone) was revealed. It was found that needlelike phases were formed both in α and β solid solutions. Moreover, in the near-β titanium alloy, pores aligned in the Frenkel plane were found. The latter finding indicated that the diffusion of alloying elements of near-β alloy is the most probable reason for the observed microstructural changes. Additionally, the “grooving” phenomenon at the α/β interface was found and it was correlated with faster diffusion through grain boundaries, rather than volume diffusion. Finally, the pore size was measured and numerically modeled. The calculated values were in good agreement with the experimental ones.

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Characterization of Precipitates in 3xxx Series Alloys with Zirconium

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.231.81 ◽

2015 ◽

Vol 231 ◽

pp. 81-85

Author(s):

Mariusz Bigaj ◽

Sonia Boczkal ◽

Monika Mitka ◽

Zbigniew Zamkotowicz ◽

Janusz Żelechowski ◽

...

Keyword(s):

Electron Microscope ◽

Electron Backscatter Diffraction ◽

Scanning Transmission Electron Microscope ◽

Phase Identification ◽

Transmission Electron ◽

Scanning Transmission ◽

Backscatter Diffraction ◽

Ebsd Method ◽

Eds Microanalysis

The study presents the results of microstructure examinations and phase identification of precipitates in AlMn alloys containing zirconium after heat treatment and rolling. Chemical composition in microareas was determined by Energy Dispersive Spectrometry (EDS) microanalysis performed in Scanning Electron Microscope (SEM-EDS) and Scanning Transmission Electron Microscope (STEM-EDS) modes. Phase identification was carried out using Electron Backscatter Diffraction (EBSD) method. Studies have shown that Al6Mn and α- Al17(Fe3.2Mn0.8)Si2 phases were formed in the melt. Microstructure examined by TEM showed the presence of finely dispersed spherical precipitates of zirconium. In the alloy with an addition of silicon and magnesium, numerous precipitates of an Mg2Si phase were also found.

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Crystallographic Mapping in Scanning and Transmission Electron Micrsocopy with Application to Semiconductor Materials

MRS Proceedings ◽

10.1557/proc-523-253 ◽

1998 ◽

Vol 523 ◽

Author(s):

D. J. Dingley ◽

S. I. Wright ◽

D. J. Dingley

Keyword(s):

Electron Microscope ◽

Electron Backscatter Diffraction ◽

Orientation Imaging Microscopy ◽

Lattice Parameter ◽

Dark Field ◽

Polycrystalline Materials ◽

Orientation Imaging ◽

Transmission Electron ◽

Dark Field Microscopy ◽

Backscatter Diffraction

AbstractThe two sister techniques, Electron Backscatter Diffraction and Orientation Imaging Microscopy which operate in a scanning electron microscope, are well established tools for the characterization of polycrystalline materials. Experiment has shown that the limiting resolution for mapping is the order of 0.1 microns. The basic techniques have been extended to include multiphase mapping. Whereas it has been possible to distinguish between phases of different crystal systems easily, it has not been possible to distinguish between phases that differ in lattice parameter by less than 5 %.An equivalent transmission electron microscope procedure has been developed. The technique couples standard hollow cone microscopy procedures with dark field microscopy. All possible dark field images that can be produced by tilting the electron beam are scanned to detect under what settings each crystal is brought into a diffracting condition. Subsequent analysis permits determination of both crystal phase and orientation.

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Fatigue Behaviour and Mechanical Properties of ECAP'ed and Thixoformed AA7075

High Temperature Materials and Processes ◽

10.1515/htmp-2013-0074 ◽

2014 ◽

Vol 33 (3) ◽

pp. 277-285 ◽

Cited By ~ 8

Author(s):

Hasan Kaya ◽

Mehmet Uçar

Keyword(s):

Electron Microscope ◽

High Hardness ◽

Fatigue Behaviour ◽

Optical Microscope ◽

Fatigue Tests ◽

Grain Structure ◽

Angular Pressing ◽

Ecap Process ◽

Transmission Electron ◽

Semi Solid

AbstractIn this study, the effects of thixoforming, both equal channel angular pressing (ECAP) and thixoforming on high cycle fatigue and fatigue surface morphology of AA7075 have been examined. Experiments are carried out with the same sample materials (AA7075) at a constant temperature (483 K) and the ``C'' route for 4 passes at ECAP process. In the process of thixoforming is 20 min at 888 K for waiting and 1 min at 673 K for pressing implemented. 140 MPa, 120 MPa and 100 MPa strength values were used at fatigue tests. The microstructural characterizations of the samples were carried out by using optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). This study is an attempt in detail to transformation fine and spherical grain structure with thixoforming process of minimized grain structure by ECAP. As a result of this study, it was seen that ECAP (1 pass) + semi-solid processing (SSP) applied samples have the highest hardness value (171 HV). When the values that are obtained after fatigue strength analyzed, SSP applied materials' property gave the best results and ECAP (1 pass) + SSP applied samples' results were second. When the both process applied materials' optimum values are investigated, it was observed that ECAP 1 pass + SSP applied material is more appropriate in terms of high hardness and fatigue life.

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TEM Sample Preparation and FIB-Induced Damage

MRS Bulletin ◽

10.1557/mrs2007.63 ◽

2007 ◽

Vol 32 (5) ◽

pp. 400-407 ◽

Cited By ~ 484

Author(s):

Joachim Mayer ◽

Lucille A. Giannuzzi ◽

Takeo Kamino ◽

Joseph Michael

Keyword(s):

Electron Microscope ◽

Focused Ion Beam ◽

Electron Backscatter Diffraction ◽

Ion Beam ◽

X Ray ◽

Transmission Electron ◽

Electron Backscatter ◽

Future Potential ◽

Backscatter Diffraction ◽

Composite Samples

AbstractOne of the most important applications of a focused ion beam (FIB) workstation is preparing samples for transmission electron microscope (TEM) investigation. Samples must be uniformly thin to enable the analyzing beam of electrons to penetrate. The FIB enables not only the preparation of large, uniformly thick, sitespecific samples, but also the fabrication of lamellae used for TEM samples from composite samples consisting of inorganic and organic materials with very different properties. This article gives an overview of the variety of techniques that have been developed to prepare the final TEM specimen. The strengths of these methods as well as the problems, such as FIB-induced damage and Ga contamination, are illustrated with examples. Most recently, FIB-thinned lamellae were used to improve the spatial resolution of electron backscatter diffraction and energy-dispersive x-ray mapping. Examples are presented to illustrate the capabilities, difficulties, and future potential of FIB.

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