scholarly journals Visualization and validation of twin nucleation and early-stage growth in magnesium

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Lin Jiang ◽  
Mingyu Gong ◽  
Jian Wang ◽  
Zhiliang Pan ◽  
Xin Wang ◽  
...  
Keyword(s):  
Early Stage ◽  
Topological Analysis ◽  
Atomistic Simulations ◽  
Twin Nucleation ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Experiment ◽  
Twinning Plane ◽  
Fundamental Understanding ◽  
Twin Growth

AbstractThe abrupt occurrence of twinning when Mg is deformed leads to a highly anisotropic response, making it too unreliable for structural use and too unpredictable for observation. Here, we describe an in-situ transmission electron microscopy experiment on Mg crystals with strategically designed geometries for visualization of a long-proposed but unverified twinning mechanism. Combining with atomistic simulations and topological analysis, we conclude that twin nucleation occurs through a pure-shuffle mechanism that requires prismatic-basal transformations. Also, we verified a crystal geometry dependent twin growth mechanism, that is the early-stage growth associated with instability of plasticity flow, which can be dominated either by slower movement of prismatic-basal boundary steps, or by faster glide-shuffle along the twinning plane. The fundamental understanding of twinning provides a pathway to understand deformation from a scientific standpoint and the microstructure design principles to engineer metals with enhanced behavior from a technological standpoint.

scholarly journals Visualization and Validation of Twin Nucleation and Early-stage Growth in Magnesium

2021 ◽  
Author(s):  
Lin Jiang ◽  
Jian Wang ◽  
Jian Wang ◽  
Zhiliang Pan ◽  
Xin Wang ◽  
...  
Keyword(s):  
Early Stage ◽  
Topological Analysis ◽  
Atomistic Simulations ◽  
Twin Nucleation ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Experiment ◽  
Twinning Plane ◽  
Fundamental Understanding ◽  
Twin Growth

Abstract The abrupt occurrence of twinning when Mg is deformed leads to a highly anisotropic response, making it too unreliable for structural use and too unpredictable for observation. Here, we describe an in-situ transmission electron microscopy experiment on Mg crystals with strategically designed geometries for visualization of a long-proposed but unverified twinning mechanism. Combining with atomistic simulations and topological analysis, we conclude that twin nucleation occurs through a pure-shuffle mechanism that requires prismatic-basal transformations. Also, we verified a crystal geometry dependent twin growth mechanism, that is the early-stage growth associated with instability of plasticity flow, which can be dominated either by slower movement of prismatic-basal boundary steps, or by faster glide-shuffle along the twinning plane. The fundamental understanding of twinning provides a pathway to understand deformation from a scientific standpoint and the microstructure design principles to engineer metals with unprecedented combinations of properties from a technological standpoint.

Combined In Situ Neutron Diffraction and Acoustic Emission of Twin Nucleation & Twin Growth in Extruded ZM20 Mg Alloy

2010 ◽  
Vol 652 ◽  
pp. 149-154 ◽  
Author(s):  
Ondrej Muránsky ◽  
Matthew R. Barnett ◽  
David G. Carr ◽  
Sven C. Vogel ◽  
E.C. Oliver
Keyword(s):  
Acoustic Emission ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Coarse Grained ◽  
Fine Grained ◽  
Grain Sizes ◽  
Twin Nucleation ◽  
Twin Growth ◽  
In Situ Neutron Diffraction

In the present work in situ neutron diffraction and acoustic emission were used concurrently to study deformation twinning in two ZM20 Mg alloys with significantly different grain sizes at room temperature. The combination of these techniques allows differentionation between the twin nucleation and the twin growth mechanisms. It is shown, that yielding and immediate post-yielding plasticity in compression is governed primarily by twin nucleation, whereas the plasticity at higher strains is governed by twin growth. The current results further suggest that yielding by twinning happens in a slightly different manner in the fine-grained as compared to the coarse-grained alloy.

scholarly journals In Situ Atomic-Scale Observation of Silver Oxidation Triggered by Electron Beam Irradiation

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1021
Author(s):  
Hui Zhang ◽  
Tao Xu ◽  
Yatong Zhu ◽  
Wen Wang ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Oxidation Process ◽  
Atomic Scale ◽  
Advanced Materials ◽  
Metal Oxidation ◽  
Beam Irradiation ◽  
Transmission Electron ◽  
Fundamental Understanding

Understanding the mechanism of metal oxidation processes is critical for maintaining the desired properties of metals and catalysts, as well as for designing advanced materials. In this work, we investigate the electron beam induced oxidation of silver using in situ transmission electron microscopy. The additions of Ag-O columns on {111} and {110} planes were captured with atomic resolution. Interestingly, oscillatory growth on {110} planes was observed, which resulted from the double effect of electron beam irradiation. It was found that not only thermodynamic factors but also kinetic factors played significant roles in morphology evolutions. These results can facilitate the fundamental understanding of the oxidation process of Ag and provide a promising approach for the fabrication of desired nanostructures.

Real Time Observations of Dislocation-Mediated Plasticity in the Epitaxial Aluminum (110) / Silicon (001) Thin Film System

2000 ◽  
Vol 6 (S2) ◽  
pp. 438-439
Author(s):  
E.A. Stach ◽  
U. Dahmen ◽  
W.D. Nix
Keyword(s):  
Real Time ◽  
Physical Vapor Deposition ◽  
Device Fabrication ◽  
Metallic Thin Films ◽  
Si Substrate ◽  
Microelectronic Devices ◽  
Transmission Electron ◽  
Fundamental Understanding ◽  
Uniform Area

The mechanical behavior of metallic thin films on silicon plays a crucial role in the performance and reliability of microelectronic devices. A substantial body of research has focused on experimental methods for determining the mechanical properties of these systems as well as their response to thermomechanical stimuli. Of particular interest is a fundamental understanding of the how these films respond to the thermal expansion stresses that develop during typical microelectronic device fabrication steps.In this work, we present a series of real time in-situ transmission electron microscopy observations of the thermomechanical response of a model metal film on silicon system. Physical vapor deposition of approximately 50 nm of aluminum onto a clean Si substrate held at 280 °C results in the creation of an epitaxial bicrystalline film with two variants of Al (110) oriented grains. In order to observe a large, uniform area during in-situ TEM thermal cycling, the Si substrate used was a SIMOX structure composed of 300 nm of Si (001) over 370 nm of buried SiO2).

In situ observation of the sodiation process in CuO nanowires

2015 ◽  
Vol 51 (52) ◽  
pp. 10443-10446 ◽  
Author(s):  
Huihui Liu ◽  
Fan Cao ◽  
He Zheng ◽  
Huaping Sheng ◽  
Lei Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrode Materials ◽  
Sodium Ion ◽  
Dynamic Evolution ◽  
In Situ Observation ◽  
Sodium Ion Batteries ◽  
Cuo Nanowires ◽  
Transmission Electron ◽  
Fundamental Understanding

We observed the dynamic evolution of the morphology and phase transformations of CuO nanowires during sodiation using in situ transmission electron microscopy. These results will facilitate our fundamental understanding of the sodiation mechanism of CuO nanostructures used as electrode materials in sodium ion batteries.

Early Stage of Oxidation of Mo3Si by In Situ Environmental Transmission Electron Microscopy

CORROSION ◽  
10.5006/2564 ◽  
2017 ◽  
Vol 74 (3) ◽  
pp. 288-294 ◽  
Author(s):  
A. Gulec ◽  
X.X. Yu ◽  
M. Taylor ◽  
A. Yoon ◽  
J.M. Zuo ◽  
...  
Keyword(s):  
Early Stage ◽  
Nanometer Scale ◽  
Environmental Transmission ◽  
New Family ◽  
High Temperature Materials ◽  
Transmission Electron ◽  
Initial Stage ◽  
Porous Sio2 ◽  
Transient Period

Mo-Si-based superalloys are of interest as a new family of high-temperature materials to replace Ni-based alloys. By means of in situ environmental transmission electron microscope, the transient period of the early oxidation of Mo3Si was investigated at the nanometer scale. As a result of a competition between loss of volatile MoO3 and association of SiO2 molecular units into pillars, a nanometer-sized porous SiO2 grows at a very initial stage of the oxidation of Mo3Si.

Effect of the Nitridation of the Sapphire (0001) Substrate on the GaN Growth

1996 ◽  
Vol 449 ◽  
Author(s):  
N. Grandjean ◽  
J. Massies ◽  
P. Vennègues ◽  
M. Laugt ◽  
M. Leroux
Keyword(s):  
Basal Plane ◽  
Early Stage ◽  
High Energy ◽  
Thin Layers ◽  
Structural Quality ◽  
High Energy Electron ◽  
Epitaxial Relationship ◽  
Sapphire Surface ◽  
Transmission Electron

ABSTRACTThe analysis of the sapphire surface nitridation by in situ reflection high-energy electron diffraction evidences the formation of a relaxed AIN layer. Its role on the early stage of the GaN growth is investigated by transmission electron microscopy (TEM). GaN crystallites of high structural quality, with the c axis perpendicular to the sapphire basal plane, are observed when the starting surface is nitridated. On the other hand, the growth of GaN on a bare substrate involves the formation of larger islands with numerous defects. TEM study reveals that the c axis of these latter crystallites is systematically tilted by about 19° with respect to the sapphire basal plane. Actually, this orientation corresponds to a particular epitaxial relationship between GaN and sapphire (0001) substrates. Finally, the optical properties of GaN thin layers are shown to be strongly dependent on the nitridation state of the sapphire surface.

scholarly journals Quantitative Differentiation of Both Free 3′-OH and 5′-OH DNA Ends Between Heat-induced Apoptosis and Necrosis

1998 ◽  
Vol 46 (9) ◽  
pp. 1051-1059 ◽  
Author(s):  
Rika Hayashi ◽  
Yuko Ito ◽  
Kenji Matsumoto ◽  
Yuko Fujino ◽  
Yoshinori Otsuki
Keyword(s):  
Dna Cleavage ◽  
Early Stage ◽  
Dna Degradation ◽  
Strand Breaks ◽  
Transmission Electron ◽  
Dna Strand ◽  
Induced Apoptosis ◽  
Apoptosis And Necrosis ◽  
Dna Ends

Cell death is roughly categorized as either apoptosis or necrosis. For better understanding of the differences in DNA cleavage between them, we performed quantitative analysis of both the 3′-OH and the 5′-OH ends of DNA strand breaks via in situ nick-end labeling (ISEL) combined with transmission electron microscopy (TEM) of both heat-induced apoptosis and necrosis in mouse B-cells derived from a lymphoma cell line. To detect the 5′-OH ends, the 3′-P ends located on the opposite side holding the 5′-OH ends were dephosphorylated into 3′-OH ends with alkaline phosphatase. As assessed by statistical analysis of both the 3′-OH and the 5′-OH ends, their labeling densities were significantly higher in both the apoptotic and the necrotic cells in the early stage than in control cells. The labeling densities increased during the apoptotic and necrotic processes, except for a decrease in the density of the 3′-OH ends in necrotic cells in the late stages. Therefore, DNA degradation in both necrosis and apoptosis provides early evidence for these processes, and both apoptosis and necrosis may share at least the first steps of DNA degradation pathways.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Sign in / Sign up

Export Citation Format

Share Document