scholarly journals The Effect of Displacement Cascades on Small Helium Bubbles in Aluminum and Gold

1994 ◽  
Vol 373 ◽  
Author(s):  
S E. Donnelly ◽  
R.C. Birtcher ◽  
C. Templier ◽  
R. Valizadeh ◽  
V. Vishnyakov
Keyword(s):  
Electron Microscopy ◽  
Molecular Dynamics ◽  
Transmission Electron Microscopy ◽  
Brownian Motion ◽  
Thermal Spike ◽  
Helium Bubbles ◽  
Thin Foils ◽  
Transmission Electron ◽  
Dynamics Simulations

AbstractThe evolution of individual helium bubbles in thin foils of gold and aluminum irradiated with 400 keV Ar+ and 200 keV Xe+ has been followed with in-situ transmission electron microscopy for a comparison between the effects of dilute (Al) and dense (Au) collision cascades. Bubble shrinkage in Al has been attributed to direct displacement of the gas out of the bubbles. Effects in Au, include the disappearance and Brownian motion of bubbles under irradiation, and are consistent with thermal spike processes seen in molecular dynamics simulations.

scholarly journals Electron Microscopy Investigation of Magnetization Process in Thin Foils and Nanostructures

2007 ◽  
Vol 1026 ◽  
Author(s):  
Pascale Bayle-Guillemaud ◽  
Aurelien Masseboeuf ◽  
Fabien Cheynis ◽  
Jean-Christophe Toussaint ◽  
Olivier Fruchart ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Anisotropy ◽  
Magnetic Induction ◽  
Perpendicular Magnetic Anisotropy ◽  
In Situ Observation ◽  
Magnetic Imaging ◽  
Thin Foils ◽  
Transmission Electron

AbstractThis paper presents investigations of magnetization configuration evolution during in-situ magnetic processes in materials exhibiting planar and perpendicular magnetic anisotropy. Transmission electron microscopy has been used to perform magnetic imaging. Fresnel contrasts in Lorentz Transmission Electron Microscopy (LTEM) and phase retrieval methods such as Transport of Intensity Equation (TIE) solving or electron holography have been implemented. These techniques are sensitive to magnetic induction perpendicular to the electron beam and can give access to a spatially resolved (resolution better than 10 nm) mapping of magnetic induction distribution and could be extended to dynamical studies during in-situ observation. Thin foils of FePd alloys with a strong perpendicular magnetic anisotropy (PMA) and self-assembled Fe dots are presented. Both are studied during magnetization processes exhibiting the capacities of in-situ magnetic imaging in a TEM.

Role of Interface Boundaries in the Deformation Behavior of TiAl Polysynthetically Twinned Crystal: In situ Transmission Electron Microscopy Deformation Study

2005 ◽  
Vol 20 (7) ◽  
pp. 1888-1901 ◽  
Author(s):  
Sung G. Pyo ◽  
Nack J. Kim
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Deformation Behavior ◽  
Localized Deformation ◽  
Deformation Twins ◽  
Thin Foils ◽  
Transmission Electron ◽  
Longitudinal Orientation

To understand the role of boundaries in the deformation behavior of TiAl, in situ straining experiments in transmission electron microscopy have been performed on thin foils of polysynthetically twinned (PST) crystal of Ti–49.3 at.% Al. The deformation behavior of PST TiAl is anisotropic, depending on the angle between the lamellar boundaries and the straining axes. For L-orientation, deformation twins and ordinary dislocations transmit across the true-twin (TT) boundaries but are reflected at the pseudo-twin (PT) and rotational order-fault (RO) boundaries. For transverse (T) orientation, deformation twins are transmitted across all TT, PT, and RO boundaries. For I-orientation, shear deformation occurs parallel to the lamellar boundaries. There is a transmission of deformation across the interphase (IP) boundary in longitudinal orientation, but deformation is blocked and reflected at the IP boundary in T-orientation. The role of the various types of boundaries in localized deformation behavior was evaluated by considering Schmid factors and geometric compatibility factors.

Oriented attachment induces fivefold twins by forming and decomposing high-energy grain boundaries

Science ◽  
2019 ◽  
Vol 367 (6473) ◽  
pp. 40-45 ◽  
Author(s):  
Miao Song ◽  
Gang Zhou ◽  
Ning Lu ◽  
Jaewon Lee ◽  
Elias Nakouzi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundaries ◽  
Palladium Nanoparticles ◽  
High Energy ◽  
Oriented Attachment ◽  
Transmission Electron ◽  
Wide Range ◽  
Dynamics Simulations

Natural and synthetic nanoparticles composed of fivefold twinned crystal domains have distinct properties. The formation mechanism of these fivefold twinned nanoparticles is poorly understood. We used in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations to demonstrate that fivefold twinning occurs through repeated oriented attachment of ~3-nanometer gold, platinum, and palladium nanoparticles. We discovered two different mechanisms for forming fivefold twinned nanoparticles that are driven by the accumulation and elimination of strain. This was accompanied by decomposition of grain boundaries and the formation of a special class of twins with a net strain of zero. These observations allowed us to develop a quantitative picture of the twinning process. The mechanisms provide guidance for controlling twin structures and morphologies across a wide range of materials.

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