scholarly journals In situ TEM study of precipitation in a quasicrystal-strengthened AL-alloy

2017 ◽  
Vol 62 (1) ◽  
pp. 5-9 ◽  
Author(s):  
T. Bončina ◽  
F. Zupanič
Keyword(s):  
Electron Microscopy ◽  
In Situ Tem ◽  
Al Alloy ◽  
Precipitation Kinetics ◽  
Transmission Electron ◽  
Heterogeneous Formations ◽  
T Phase ◽  
Icosahedral Quasicrystalline ◽  
Copper Mould

Abstract Precipitation kinetics and mechanisms within an Al-Mn-Be-Cu quasicrystal strengthened alloy at 300°C were studied using in-situ transmission electron microscopy. The alloy was cast into a copper mould. Quasicrystalline precipitates formed throughout the Al-rich solid solution, whilst heterogeneous formations of Al2Cu and T-phase occurred on icosahedral quasicrystalline particles formed during solidification. The formation of quasicrystalline particles and T-phase was limited by manganese diffusivity, whilst that of Al2Cu by copper diffusivity. The precipitation produced only a small hardening effect.

Clarifying the Role of Mg2Si and Si in Localized Corrosion of Aluminum Alloys by Quasi In Situ Transmission Electron Microscopy

CORROSION ◽  
10.5006/3457 ◽  
2020 ◽  
Vol 76 (5) ◽  
pp. 464-475 ◽  
Author(s):  
Shravan K. Kairy ◽  
Nick Birbilis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnesium Silicide ◽  
Localized Corrosion ◽  
In Situ Tem ◽  
Al Alloy ◽  
Transmission Electron ◽  
Al Matrix

The role of magnesium silicide (Mg2Si) and silicon (Si) particles in the localized corrosion of aluminum (Al) alloys was investigated herein. Sub-micrometer-sized Mg2Si and Si particles were grown in the Al matrix of Al-Mg-Si and Al-Si alloys, respectively, and characterized by transmission electron microscopy (TEM). A quasi in situ TEM technique was used to study an identical location containing Mg2Si or Si particle in the Al matrix, prior to and following a period of immersion in 0.1 M NaCl at pH 6, 2, and 12. At pH 6 and 2, Mg2Si was initially “anodic,” preferentially dealloying via selective dissolution of Mg, resulting in the development of SiO-rich remnants that are electrochemically inert. The SiO-rich remnants at pH 2 physically detached from the Al matrix. Silicon particles were electrochemically inert at pH 6, while “cathodic” at pH 2, dissolving the Al matrix at their periphery. It was observed that copper (Cu) was redeposited on Si particles at pH 2. At pH 12, Mg2Si and Si were “cathodic” to the Al matrix. This study clarifies, and provides new insights into, the characteristics of Al alloy physical manifestation of corrosion associated with Mg2Si and Si at the nanoscale.

scholarly journals Unravelling the characteristics of Al-alloy corrosion at the atomic to nanometre scale by transmission electron microscopy

2020 ◽  
Vol 326 ◽  
pp. 01007
Author(s):  
Shravan K. Kairy ◽  
Nick Birbilis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Al Alloy ◽  
Second Phase ◽  
Clear Understanding ◽  
Transmission Electron ◽  
Second Phase Particles ◽  
Al Matrix

The localised corrosion associated with Mg2Si in the Al-matrix of an Al-Mg-Si alloy was studied in 0.1 M NaCl at pH 6 by quasi in-situ transmission electron microscopy. Herein, physical imaging of corrosion at the atomic to nanometre scale was performed. Phase transformation and subsequent chemical composition variations associated with the localised corrosion of Mg2Si were studied. It was observed that corrosion initiated upon Mg2Si, often preferentially at the interface with the Al-matrix, and propagated until Mg2Si was completely dealloyed by Mg-dissolution, resulting in an amorphous SiO-rich phase remnant. The SiO-rich remnant became electrochemically inert and did not initiate corrosion in the Al-matrix. This study provides a clear understanding on the localised corrosion of Al-alloys associated with Mg2Si. In addition, the methodology followed in this study can also be applied to understand the role of precipitates and second phase particles in the localised corrosion of Al-alloy systems.

In-Situ TEM Observation of Electromigration Damage by Surface or Interface Diffusion in Al and Al Alloy Films

1991 ◽  
Vol 225 ◽  
Author(s):  
C. Y. Chang ◽  
R. W. Vook
Keyword(s):  
Grain Size ◽  
Diffusion Mechanism ◽  
In Situ Tem ◽  
Al Alloy ◽  
Linear Temperature ◽  
Alloy Films ◽  
Interface Diffusion ◽  
Transmission Electron ◽  
Dc Current

ABSTRACTIn-situ transmission electron microscope (TEM) electromigration damage (EMD) tests were performed on pure Al films which were thermally evaporated onto oxidized silicon wafers under different deposition conditions. Three different aluminum alloy films, Al-2wt%Cu, Al-8wt%Cu, and Al-2wt%Cu-lwt%Si were also examined. TEM images were recorded photographically and by a video camcorder. The sample stripes were stressed by a high DC current density (≈1.5 MA/cm2). A linear temperature ramp (5°C/min) was supplied by an external, computer controlled heater. The morphology of EMD-induced voids was found to be strongly dependent on microstructure. In small grain size Al stripes, EMD occurred by the formation of void “fingers” which propagated in an almost random manner. In large grain size Al and Al alloy stripes, the EMD-elongated voids propagated approximately parallel to each other and along the field direction. They were preceded with clearly identifiable local thinning. The thinned regions often had crystallographic edges. Contrary to the commonly held belief that EMD occurs only by a grain boundary diffusion mechanism, the present study clearly shows that surface or interface diffusion was the dominant, latter stage EMD failure mode in large grain size films.

In situ TEM observation of Au–Cu2O core–shell growth in liquids

Nanoscale ◽  
2019 ◽  
Vol 11 (21) ◽  
pp. 10486-10492 ◽  
Author(s):  
Fu-Chun Chen ◽  
Jui-Yuan Chen ◽  
Ya-Hsuan Lin ◽  
Ming-Yu Kuo ◽  
Yung-Jung Hsu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Shell Growth ◽  
Core Shell ◽  
In Situ Tem ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Liquid Cell ◽  
Different Shapes ◽  
Core Shell Nanoparticles

The formation of different shapes Au–Cu2O core–shell nanoparticles was investigated by in situ liquid cell transmission electron microscopy (LCTEM).

In-situ TEM studies of magnetization reversal processes in magnetic nanostructures

2005 ◽  
Vol 907 ◽  
Author(s):  
Amanda K Petford-Long ◽  
Thomas Bromwich ◽  
Amit Kohn ◽  
Victoria Jackson ◽  
Takeshi Kasama ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetization Reversal ◽  
Giant Magnetoresistance ◽  
Magnetic Nanostructures ◽  
Magnetic Domain ◽  
Ferromagnetic Material ◽  
In Situ Tem ◽  
Transmission Electron

AbstractOne of the most widely studied types of magnetic nanostructure is that used in devices based on the giant magnetoresistance (GMR) or tunnel magnetoresistance (TMR) phenomena. In order to understand the behaviour of these materials it is important to be able to follow their magnetisation reversal mechanism, and one of the techniques enabling micromagnetic studies at the sub-micron scale is transmission electron microscopy. Two techniques can be used: Lorentz transmission electron microscopy and off-axis electron holography, both of which allow the magnetic domain structure of a ferromagnetic material to be investigated dynamically in real-time with a resolution of a few nanometres. These techniques have been used in combination with in situ magnetizing experiments, to carry out qualitative and quantitative studies of magnetization reversal in a range of materials including spin-tunnel junctions, patterned thin film elements and magnetic antidot arrays. Quantitative analysis of the Lorentz TEM data has been carried out using the transport of intensity equation (TIE) approach.

NANOMECHANICS OF INDIVIDUAL ZINC OXIDE NANOBELTS MEASURED BY IN SITU TRANSMISSION ELECTRON MICROSCOPY

2006 ◽  
Vol 05 (06) ◽  
pp. 951-958 ◽  
Author(s):  
XUEDONG BAI ◽  
EN GE WANG ◽  
ZHONG LIN WANG
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Zinc Oxide ◽  
Rectangular Cross Section ◽  
In Situ Tem ◽  
Resonance Modes ◽  
Bending Modulus ◽  
Transmission Electron ◽  
Potential Applications

Zinc oxide nanobelts, grown by a solid–vapor phase thermal sublimation process, are stimulating extensive interest because of their semiconducting and piezoelectric properties, diverse functionalities and chemical stability. For nanomanipulation and nanomeasurement of an individual ZnO nanobelts, in situ transmission electron microscopy (TEM) technique is a unique approach. In this paper, mechanical resonance of a single ZnO nanobelt, induced by an alternative electric field, was studied by in situ TEM. Due to the rectangular cross-section of the nanobelt, two fundamental resonance modes have been observed in corresponding to two orthogonal transverse vibration directions, showing the versatile applications of nanobelts as nanocantilevers and nanoresonators. The bending modulus of the ZnO nanobelts was measured to be ~ 52 GPa and the damping time constant of the resonance in vacuum of 10–8 Torr was ~ 1.2 ms. The ZnO nanobelts are promising in potential applications as nanocantilevers, nanoresonators and nanoactuators.

In-Situ Transmission Electron Microscopy of the Solid-Phase Epitaxial Growth of GaAs: Sample Preparation and Artifact Characterization

1997 ◽  
Vol 480 ◽  
Author(s):  
K. B. Belay ◽  
M. C. Ridgway ◽  
D. J. Llewellyn
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Epitaxial Growth ◽  
Solid Phase ◽  
Ion Beam ◽  
Ex Situ ◽  
In Situ Tem ◽  
Transmission Electron

AbstractIn-situ transmission electron microscopy (TEM) has been used to characterize the solidphase epitaxial growth of amorphized GaAs at a temperature of 260°C. To maximize heat transfer from the heated holder to the sample and minimize electron-irradiation induced artifacts, non-conventional methodologies were utilized for the preparation of cross-sectional samples. GaAs (3xI) mm rectangular slabs were cut then glued face-to-face to a size of (6x3) mm stack by maintaining the TEM region at the center. This stack was subsequently polished to a thickness of ~ 200 ýtm. A 3 mm disc was then cut from it using a Gatan ultrasonic cutter. The disc was polished and dimpled on both sides to a thickness of ~15 mimT.h is was ion-beam milled at liquid nitrogen temperature to an electron-transparent layer. From a comparison of in-situ and ex-situ measurements of the recrystallization rate, the actual sample temperature during in-situ characterization was estimated to deviate by ≤ 20°C from that of the heated holder. The influence of electron-irradiated was found to be negligible by comparing the recrystallization rate and microstructure of irradiated and unirradiated regions of comparable thickness. Similarly, the influence of “thin-foil effect” was found to be negligible by comparing the recrystallization rate and microstructure of thick and thin regions, the former determined after the removal of the sample from the microscope and further ion-beam milling of tens of microns of material. In conclusion, the potential influence of artifacts during in-situ TEM can be eliminated by the appropriate choice of sample preparation procedures.

Formation of Pb Inclusions in Si by Ion Implantation

1997 ◽  
Vol 504 ◽  
Author(s):  
V. S. Touboltsev ◽  
E. Johnson ◽  
U. Dahmen ◽  
A. Johansen ◽  
L. Sarholt ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Average Concentration ◽  
Supersaturated Solution ◽  
In Situ Tem ◽  
Tem Analysis ◽  
Host Matrix ◽  
Transmission Electron ◽  
Main Fraction ◽  
20 Nm

AbstracrSi<110> single crystals were implanted at a temperature of 835 K with 150 keV Pb+ ions to a fluence of 1·1020 m−2 corresponding to an average concentration of 2–3 at%. The implanted samples have been studied by Rutherford Backscattering (RBS)/channeling and transmission electron microscopy (TEM) techniques. In as-implanted samples the main fraction of implanted Pb was located on substitutional sites in the Si matrix thus providing a highly supersaturated solution of Pb in Si. Spontaneous precipitation of Pb, giving rise to formation of nanosized Pb inclusions, was found to take place only in the peak region of the implantation. TEM analysis showed that the Pb precipitates had sizes from about 2 to 20 nm and that they grew in parallel cube orientation relationship with the host matrix. The shape of the inclusions was found to be approximately cuboctahedral with poorly developed {111} and {100} facets.In-situ RBS/channeling heating/cooling experiments on both as-implanted samples and samples previously furnace-annealed at 1175 K showed a distinct melting/solidification hysteresis of the Pb inclusions around the bulk melting point for Pb at 600 K. These results were verified by in-situ TEM heating/cooling experiments on as-implanted samples.

In Situ TEM Heating Study of the γ Lamellae Formation inside the α2 Matrix of a Ti-45Al-7.5Nb Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 1365-1368 ◽  
Author(s):  
Li Mei Cha ◽  
Helmut Clemens ◽  
Gerhard Dehm ◽  
Zao Li Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ex Situ ◽  
In Situ Tem ◽  
Transmission Electron ◽  
Initial Stage ◽  
Heat Treated ◽  
The Matrix ◽  
In Situ Heating

In-situ heating transmission electron microscopy (TEM) was employed to investigate the initial stage of lamellae formation in a high Nb containing γ-TiAl based alloy. A Ti-45Al-7.5Nb alloy (at %), which was heat treated and quenched in a non-equilibrium state such that the matrix consists of ordered a2 grains, was annealed inside a TEM up to 750 °C. The in-situ TEM study reveals that g laths precipitate in the a2 matrix at ~ 750 °C possessing the classical Blackburn orientation relationship, i.e. (0001)a2 // (111)g and [11-20]a2 // <110]g. The microstructure of the in-situ TEM experiment is compared to results from ex-situ heating and subsequent TEM studies.

Towards Property Nanomeasurments By In-Situ TEM

2000 ◽  
Vol 6 (S2) ◽  
pp. 64-65
Author(s):  
Z.L. Wang ◽  
R.P. Gao ◽  
Z.G. Bai ◽  
Z.R. Dai ◽  
P. Poncharal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Resonance Phenomenon ◽  
In Situ Tem ◽  
Bending Modulus ◽  
Quantitative Measurements ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Tunable Frequency ◽  
Alternating Voltage

Characterizing the physical properties of individual nanostructures is rather challenging because of the difficulty in manipulating the objects of sizes from nanometer to micrometer. Most of the nanomeasurements have been carried using STM and AFM. In this presentation, we demonstrate that transmission electron microscopy can be a powerful tool for quantitative measurements the mechanical, electrical and thermodynamic properties of a single nanostructure, such as a carbon nanotube or a nanoparticle.Using a customer-built specimen holder, in-situ measurements on the mechanical properties of carbon nanotubes has been carried out using the resonance phenomenon induced by an externally applied alternating voltage [1]. If an oscillating voltage is applied on the nanotube with tunable frequency, resonance can be induced (Fig. 1). The bending modulus is calculated from the resonance frequency. The bending modulus is as high as 1.2 TPa (as strong as diamond) for nanotubes with diameters smaller than 8 nm, and it drops to as low as 0.2 TPa for those with diameters larger than 30 nm.

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