Influence of Severe Plastic Deformation on Microstructure, Strength and Electrical Conductivity of Aged Al–0.4Zr(Wt.%) Alloy

2018 ◽  
Vol 55 (1) ◽  
pp. 92-101 ◽  
Author(s):  
T.S. Orlova ◽  
A.M. Mavlyutov ◽  
T.A. Latynina ◽  
E.V. Ubyivovk ◽  
M.Yu. Murashkin ◽  
...  
Keyword(s):  
Solid Solution ◽  
Electrical Conductivity ◽  
Ambient Temperature ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
Average Diameter ◽  
Strengthening Mechanism ◽  
X Ray ◽  
Transmission Electron ◽  
Backscatter Diffraction

Abstract. Microstructure evolution of an Al-0.4Zr(wt.%) alloy after isothermal aging (AG) and subsequent high pressure torsion (HPT) and its impact on strength and electrical conductivity has been investigated. Microstructure was characterized by X-ray diffraction, electron backscatter diffraction, transmission electron microscopy (TEM) and electron energy-dispersive X-ray spectroscopy in TEM. The initial Al-0.4Zr(wt.%) alloy obtained by combined casting and rolling presents solid solution of Zr in Al matrix. Aging at 375 °C for 60 h leads to formation of uniformly distributed metastable Al3Zr precipitates with the average diameter of 13 nm, resulting thereby in a decrease of strength sUTS from 128 to 95 MPa and in increase of conductivity from 50.7 to 58.8% IACS at ambient temperature. The subsequent HPT processing leads to grain refinement and partial dissolution of the Al3Zr precipitates that is accompanied by enrichment of solid solution by Zr atoms and by coarsening of the remaining Al3Zr precipitates. The combination of AG and HPT provides the strength and the conductivity at ambient temperature which do not decrease under annealing up to 230 °C. Moreover, additional strengthening accompanied by an increase in conductivity was found for AG-HPT samples after annealing at Tan=230 °C for 1 h, that provides the best combination of the strength of sUTS=142 MPa and the conductivity of 58.3% IACS. Contribution of different possible mechanisms into strength and charge scattering are analyzed on the basis of specific microstructural features. The analysis indicates a suppression of strengthening by the Orowan mechanism in AG and AG-HPT samples. In all the studied states, i.e. initial, after AG, and subsequent HPT, grain boundary strengthening is found to be the main strengthening mechanism.

scholarly journals Effects of Annealing Temperature on Recrystallization Texture and Microstructure Uniformity of High Purity Tantalum

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 75 ◽  
Author(s):  
Jialin Zhu ◽  
Chao Deng ◽  
Yahui Liu ◽  
Nan Lin ◽  
Shifeng Liu
Keyword(s):  
Low Temperature ◽  
Electron Backscatter Diffraction ◽  
Stored Energy ◽  
X Ray Diffraction ◽  
Center Layer ◽  
X Ray ◽  
Texture Intensity ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Backscatter Diffraction

One hundred and thirty-five degree clock rolling significantly improves the texture homogeneity of tantalum sheets along the thickness, but a distinctly fragmented substructure is formed within {111} (<111>//normal direction (ND)) and {100} (<100>//ND) deformation grains, which is not suitable to obtain a uniform recrystallization microstructure. Thus, effects of different annealing temperatures on the microstructure and texture heterogeneity of tantalum sheets along the thickness were investigated by X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Results show that the texture distribution along θ-fiber and γ-fiber is irregular and many large grains with {111} orientation develop during annealing at high temperature. However, low-temperature annealing can not only weaken the texture intensity in the surface and the center layer but also introduce a more uniform grain size distribution. This result can be attributed to the subgrain-nucleation-dominated recrystallization mechanism induced by recovery at low temperature, and moreover, a considerable decline of recrystallization driving force resulting from the release of stored energy in the deformation matrix.

Synthesis of New-structured PbTiO3 Nanowires With Reversible Bending Properties

2014 ◽  
Vol 67 (5) ◽  
pp. 790
Author(s):  
Jiang Wang ◽  
Jian Li ◽  
Youwen Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Backscatter Diffraction ◽  
X Ray Diffraction ◽  
Acicular Crystal ◽  
One Dimensional ◽  
X Ray ◽  
Transmission Electron ◽  
Bending Process ◽  
Backscatter Diffraction

One-dimensional PbTiO3 nanowires 40–500 nm in diameter and ~400 μm in length were synthesized via a hydrothermal strategy and characterized by X-ray diffraction, electron backscatter diffraction, scanning electron microscopy, and transmission electron microscopy. The results show that the PbTiO3 nanowires exhibit a new acicular crystal structure, which is a tetragonal superstructure composed of a large unit cell of 40 atoms (Pb : Ti : O = 1 : 1 : 3) with a = 12.35 Å, c = 3.83 Å. The PbTiO3 has a feature of unidirectional bending when observed through transmission electron microscopy several times. The bending can be controlled by the electron beam intensity in transmission electron microscopy and the bending process is reversible. Moreover, a possible mechanism for the bending behaviour was also studied, which indicates that macroscopic polarization is in the {110} plane and the direction is not consistent with the electric field, giving the possible driving force for the bending.

scholarly journals Evolution Of Precipitate Morphology During Extrusion In Mg ZK60A Alloy

2015 ◽  
Vol 60 (2) ◽  
pp. 1423-1426 ◽  
Author(s):  
J. Park ◽  
K.H. Jung ◽  
G.A. Lee ◽  
M. Kawasaki ◽  
B. Ahn
Keyword(s):  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Extrusion Process ◽  
Formation Mechanisms ◽  
Precipitate Morphology ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Evolution Of Precipitates

Abstract In this study, a continuously casted ZK60A magnesium alloy (Mg-Zn-Zr) was extruded in two different extrusion ratios, 6:1 and 10:1. The evolution of precipitates was investigated on the two extruded materials and compared with that of as-casted material. The microstructural analysis was performed by electron backscatter diffraction and transmission electron microscopy, and the compositional information was obtained using energy-dispersive X-ray spectroscopy. Several distinct morphologies of precipitates were observed, such as dot, rod, and disk shaped. The formation mechanisms of those precipitates were discussed with respect to the heat and strain during the extrusion process.

Crystallographic study of grain refinement of Al by Nb addition

2014 ◽  
Vol 47 (2) ◽  
pp. 770-779 ◽  
Author(s):  
Feng Wang ◽  
Dong Qiu ◽  
Zhi-Lin Liu ◽  
John A. Taylor ◽  
Mark A. Easton ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Refinement ◽  
Electron Backscatter Diffraction ◽  
Point Of View ◽  
Orientation Relationships ◽  
Matching Model ◽  
X Ray ◽  
Edge Matching ◽  
Transmission Electron ◽  
Backscatter Diffraction

The grain refinement of Al by the addition of a small amount of peritectic-forming solute, Nb, has been studied from the crystallographic point of view. Combining the observations of optical microscopy and scanning electron microscopy with the results of energy-dispersive X-ray spectroscopy and X-ray diffraction, it is confirmed that the particles observed at or near the grain centres of refined Al alloys are pro-peritectic Al3Nb particles. The crystallographic matching between the Al3Nb particles and Al grains has also been evaluated using an edge-to-edge matching model and further verified using electron backscatter diffraction and transmission electron microscopy. It is found that there are reproducible crystallographic orientation relationships between the Al3Nb particles and Al grains, and the experimental results are consistent with the predictions of the edge-to-edge matching model. This implies that the pro-peritectic Al3Nb particles are favourable nucleation sites for Al grains from the crystallographic point of view. Furthermore, the analysis of the size distribution of Al3Nb particles reveals that the Al3Nb particles at the grain centres have relatively large particle size, which also corroborates the high potency of Al3Nb according to the free growth model. It is therefore concluded that the significant grain refinement resulting from the addition of Nb is predominantly attributed to thein situformed Al3Nb particles which promote grain refinementviaenhanced heterogeneous nucleation.

Peculiarities in the Texture Formation of Intermetallic Compounds Deformed by High Pressure Torsion

2014 ◽  
Vol 1760 ◽  
Author(s):  
Christine Tränkner ◽  
Aurimas Pukenas ◽  
Jelena Horky ◽  
Michael Zehetbauer ◽  
Werner Skrotzki
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
High Energy ◽  
X Ray ◽  
Local Texture ◽  
Large Rotations ◽  
Electron Backscatter ◽  
Shear Strains ◽  
Backscatter Diffraction

ABSTRACTNiAl, YCu and TiAl polycrystals with B2 and L10 structure, respectively, have been deformed by high pressure torsion (HPT) at temperatures between 20°C and 500°C at a hydrostatic pressure of 8 GPa to high shear strains. Local texture measurements were done by diffraction of high-energy synchrotron radiation and X-ray microdiffraction. In addition, the microstructure was analyzed by electron backscatter diffraction (EBSD). Besides typical shear components an oblique cube component is observed with quite large rotations about the transverse direction. Based on the temperature dependence of this component as well as on microstructure investigations it is concluded that it is formed by discontinuous dynamic recrystallization. The influence of high pressure on recrystallization of intermetallics at low temperatures is discussed.

scholarly journals TEM Sample Preparation and FIB-Induced Damage

MRS Bulletin ◽  
2007 ◽  
Vol 32 (5) ◽  
pp. 400-407 ◽  
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.

Deformation-Induced Solid-State Amorphization in a Nanostructured Al-Mg Alloy Processed by High Pressure Torsion

2015 ◽  
Vol 817 ◽  
pp. 627-633 ◽  
Author(s):  
Man Ping Liu ◽  
Xue Feng Xie ◽  
Zhen Ya Zhang ◽  
Hui Wang ◽  
Hans J. Roven
Keyword(s):  
High Pressure ◽  
Solid State ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
Mg Alloy ◽  
Strong Interactions ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Backscatter Diffraction ◽  
State Amorphization

This work reports the experimental evidence of localized solid-state amorphization (SSA) in a nanostructured Al–Mg alloy processed by high pressure torsion at room temperature. Electron backscatter diffraction analysis indicated that the deformed alloy had a very small average grain size of about 79 nm. High-resolution transmission electron microscopy (HRTEM) observations illustrated that the deformation-induced SSA were frequently located in the vicinity of grain boundaries (GBs) and GB junctions where high density dislocations, severe lattice distortion, deformation twins and stacking faults coexisted in the deformed alloy. The SSA phenomenon may primarily be attributed to the strong interactions of the high dislocation densities, GBs and the planar interfaces. A possible formation process of amorphization is proposed based on the HRTEM investigations. The present results suggest that the crystalline-to-amorphous transformation could also occur in binary Al–Mg alloys through severe plastic deformation that are usually produced by rapid solidification.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

scholarly journals Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

2021 ◽  
Author(s):  
A. Leineweber ◽  
M. Löffler ◽  
S. Martin
Keyword(s):  
Phase Equilibria ◽  
Electron Backscatter Diffraction ◽  
Metastable Phase ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Ordered Phases ◽  
Backscatter Diffraction ◽  
Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

scholarly journals Synthesis of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

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