Helium Implantation of Ultrafine Grained Tungsten within a TEM

2014 ◽  
Vol 1645 ◽  
Author(s):  
K. Hattar ◽  
O. El-Atwani ◽  
M. Efe ◽  
T.J. Novakowski ◽  
A. Suslova ◽  
...  
Keyword(s):  
Nuclear Reactors ◽  
Ion Irradiation ◽  
Tungsten Alloys ◽  
Helium Bubbles ◽  
Transmission Electron ◽  
Radiation Properties ◽  
Ultrafine Grained ◽  
Theoretical Predictions ◽  
Helium Implantation ◽  
Future Work

ABSTRACTMany theoretical predictions have suggested that the confined length scales and increased interface density of various nanostructured materials may result in desired thermal, mechanical, and radiation properties. An important aspect of this for next generation nuclear reactors is understanding the change in swelling resulting from helium evolution in tungsten alloys, as a function of grain size and grain boundary type. This study investigated this using a new ion irradiation transmission electron microscope (TEM) facility that has been developed at Sandia National Laboratories and is capable of ion implanting helium at energies up to 20 keV. It was demonstrated in this feasibility study that helium could be implanted into an ultrafine grained tungsten TEM sample produced by severe plastic deformation. The size and density of the helium bubbles formed during the experiment appear nearly constant; while the larger voids formed appear to be dependent on the local microstructure. Future work is underway to both optimize the facility, as well as better understand the evolution of ultrafine grained tungsten resulting from both helium implantation and displacement damage.

Superior Radiation Resistance of ODS Ferritic Steels

2010 ◽  
Vol 654-656 ◽  
pp. 2791-2794 ◽  
Author(s):  
Ryuta Kasada ◽  
Hiromasa Takahashi ◽  
Hirotatsu Kishimoto ◽  
Kentaro Yutani ◽  
Akihiko Kimura
Keyword(s):  
Ferritic Steel ◽  
Ion Irradiation ◽  
Oxide Dispersion Strengthened ◽  
Preferential Formation ◽  
Nano Oxide ◽  
Dual Beam ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxide Particles ◽  
Helium Implantation

The oxide dispersion strengthened (ODS) ferritic steel and non-ODS reduced-activation ferritic (RAF) steel were irradiated at 773 K by means of a dual-beam ion irradiation technique to a dose of 0.4 dpa with simultaneous helium implantation up to 1000 appm. Microstructural changes were investigated by transmission electron microscopy. The RAF steel showed a preferential formation of cavities at grain boundaries, precipitate interfaces and dislocations. In contrast, the ODS ferritic steel showed a homogeneous and fine distribution of cavities in the matrix. This paper discusses the superior resistance of the ODS ferritic steel against development of cavities in terms of the effects of nano-oxide particles dispersed in the matrix.

HRTEM Study of the Role of Nanoparticles in ODS Ferritic Steel under Dual-Ion Irradiation

2011 ◽  
Vol 1296 ◽  
Author(s):  
Luke Hsiung ◽  
Scott Tumey ◽  
Michael Fluss ◽  
Yves Serruys ◽  
Francois Willaime
Keyword(s):  
Mechanical Alloying ◽  
Ferritic Steel ◽  
Ion Irradiation ◽  
Complex Oxide ◽  
Helium Bubbles ◽  
Ods Steel ◽  
Transmission Electron ◽  
Radiation Induced ◽  
State Amorphization

ABSTRACTStructures of nanoparticles and their role in dual-ion irradiated Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y2O3 (K3) ODS ferritic steel produced by mechanical alloying (MA) were studied using high-resolution transmission electron microscopy (HRTEM) techniques. The observation of Y4Al2O9 complex-oxide nanoparticles in the ODS steel imply that decomposition of Y2O3 in association with internal oxidation of Al occurred during mechanical alloying. HRTEM observations of crystalline and partially crystalline nanoparticles larger than ~2 nm and amorphous cluster-domains smaller than ~2 nm provide an insight into the formation mechanism of nanoparticles/clusters in MA/ODS steels, which we believe involves solid-state amorphization and re-crystallization. The role of nanoparticles/clusters in suppressing radiation-induced swelling is revealed through TEM examinations of cavity distributions in (Fe + He) dual-ion irradiated K3-ODS steel. HRTEM observations of helium-filled cavities (helium bubbles) preferably trapped at nanoparticle/clusters in dual-ion irradiated K3-ODS are presented.

scholarly journals Helium Bubbles and Blistering in a Nanolayered Metal/Hydride Composite

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5393
Author(s):  
Caitlin A. Taylor ◽  
Eric Lang ◽  
Paul G. Kotula ◽  
Ronald Goeke ◽  
Clark S. Snow ◽  
...  
Keyword(s):  
Ex Situ ◽  
Metallic Multilayers ◽  
Helium Bubble ◽  
Helium Bubbles ◽  
Transmission Electron ◽  
The Matrix ◽  
Multilayered Composites ◽  
Helium Implantation ◽  
Thin Film Composites

Helium is insoluble in most metals and precipitates out to form nanoscale bubbles when the concentration is greater than 1 at.%, which can alter the material properties. Introducing controlled defects such as multilayer interfaces may offer some level of helium bubble management. This study investigates the effects of multilayered composites on helium behavior in ion-implanted, multilayered ErD2/Mo thin film composites. Following in-situ and ex-situ helium implantation, scanning and transmission electron microscopy showed the development of spherical helium bubbles within the matrix, but primarily at the layer interfaces. Bubble linkage and surface blistering is observed after high fluence ex-situ helium implantation. These results show the ability of metallic multilayers to alter helium bubble distributions even in the presence of a hydride layer, increasing the lifetime of materials in helium environments.

scholarly journals EFFECT OF ARGON-ION IRRADIATION ON CAVITY FORMATION AND EVOLUTION IN 18Cr10NiTi AUSTENITIC STEEL

2020 ◽  
pp. 27-32
Author(s):  
G.D. Tolstolutskaya ◽  
S.A. Karpov ◽  
A.S. Kalchenko ◽  
I.E. Kopanets ◽  
A.V. Nikitin ◽  
...  
Keyword(s):  
Ion Irradiation ◽  
Dose Range ◽  
Swelling Behavior ◽  
Transmission Electron ◽  
Formation And Evolution ◽  
Helium Implantation ◽  
Argon Ions ◽  
Lower Temperature ◽  
Average Size ◽  
Argon Ion

The swelling behavior of 18Cr10NiTi austenitic stainless steel irradiated with energetic Ar-ions in the dose range of 40…105 displacements per atom (dpa) with simultaneously implanted argon to the levels of 0.08…6.3 at.% at temperatures of 550…700 ºC was investigated. Transmission electron microscopy (TEM) has been used to study the microstructure evolution and to determine the dependence of swelling on the damage and Ar concentration. It is shown that the highest density and average size of the cavities was observed in the region of the calculated peak damage and Ar concentration. Argon was found to promote cavity swelling at lower temperature. At simultaneous creation of defects and argon implantation it was found a shift of swelling curve to higher temperatures compared to metallic-ion irradiation. The cavity swelling behavior of an austenitic 18Cr10NiTi steel irradiated with energetic argon ions are compared with those resulting from helium implantation.

Helium-induced porous layer formation in Silicon.

1987 ◽  
Vol 107 ◽  
Author(s):  
A. Van Veen ◽  
C.C. Griffioen ◽  
J.H. Evans
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Porous Layer ◽  
Low Dose ◽  
Layer Formation ◽  
Helium Bubbles ◽  
Transmission Electron ◽  
Helium Implantation ◽  
The Stability

AbstractThe annealing behaviour of helium bubbles formed by ambient temperature 10 keV helium implantation into silicon has been studied using transmission electron microscopy (TEM) and helium desorption spectroscopy (HDS). Although the TEM results indicated conventional bubble annealing processes due to bubble migration and coalescence, the HDS data demonstrated that helium can permeate out of bubbles in silicon around 1000K to leave behind empty cavities, thus giving a porous layer coincident with the original helium implant profile.The addition of a low dose of implanted oxygen to the silicon-helium samples has been shown to strongly improve the stability of the porous layer, at least up to 1300K.

A crystallographic analysis of the CoSi/Si(111) interface using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 574-575
Author(s):  
A.C. Daykin ◽  
C.J. Kiely ◽  
R.C. Pond ◽  
J.L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Structure ◽  
Room Temperature ◽  
Theoretical Method ◽  
Crystallographic Analysis ◽  
Si Substrate ◽  
Transmission Electron ◽  
Theoretical Predictions

When CoSi2 is grown onto a Si(111) surface it can form in two distinct orientations. A-type CoSi2 has the same orientation as the Si substrate and B-type is rotated by 180° degrees about the [111] surface normal.One method of producing epitaxial CoSi2 is to deposit Co at room temperature and anneal to 650°C.If greater than 10Å of Co is deposited then both A and B-type CoSi2 form via a number of intermediate silicides .The literature suggests that the co-existence of A and B-type CoSi2 is in some way linked to these intermediate silicides analogous to the NiSi2/Si(111) system. The phase which forms prior to complete CoSi2 formation is CoSi. This paper is a crystallographic analysis of the CoSi2/Si(l11) bicrystal using a theoretical method developed by Pond. Transmission electron microscopy (TEM) has been used to verify the theoretical predictions and to characterise the defect structure at the interface.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

scholarly journals In-Situ TEM Annealing Observation of Helium Bubble Evolution in Pre-Irradiated FeCoNiCrTi0.2 Alloys

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3727
Author(s):  
Huanhuan He ◽  
Zhiwei Lin ◽  
Shengming Jiang ◽  
Xiaotian Hu ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Vacuum Arc ◽  
In Situ Tem ◽  
Face Centered Cubic ◽  
Helium Bubble ◽  
High Entropy ◽  
Helium Bubbles ◽  
Transmission Electron ◽  
Bubble Evolution ◽  
Face Centered

The FeCoNiCrTi0.2 high-entropy alloys fabricated by vacuum arc melting method, and the annealed pristine material, are face centered cubic structures with coherent γ’ precipitation. Samples were irradiated with 50 keV He+ ions to a fluence of 2 × 1016 ions/cm2 at 723 K, and an in situ annealing experiment was carried out to monitor the evolution of helium bubbles during heating to 823 and 923 K. The pristine structure of FeCoNiCrTi0.2 samples and the evolution of helium bubbles during in situ annealing were both characterized by transmission electron microscopy. The annealing temperature and annealing time affect the process of helium bubbles evolution and formation. Meanwhile, the grain boundaries act as sinks to accumulate helium bubbles. However, the precipitation phase seems have few effects on the helium bubble evolution, which may be due to the coherent interface and same structure of γ’ precipitation and matrix.

scholarly journals Effects of particulates and lipids on the hydraulic conductivity of Matrigel

2008 ◽  
Vol 105 (2) ◽  
pp. 621-628 ◽  
Author(s):  
William J. McCarty ◽  
Melissa F. Chimento ◽  
Christine A. Curcio ◽  
Mark Johnson
Keyword(s):  
Extracellular Matrix ◽  
Hydraulic Conductivity ◽  
Weight Fraction ◽  
Low Density Lipoproteins ◽  
Blood Vessel Wall ◽  
Connective Tissues ◽  
Rigid Particles ◽  
Ldl Particles ◽  
Transmission Electron ◽  
Theoretical Predictions

The hydraulic conductivity of a connective tissue is determined both by the fine ultrastructure of the extracellular matrix and the effects of larger particles in the interstitial space. In this study, we explored this relationship by examining the effects of 30- or 90-nm-diameter latex nanospheres or low-density lipoproteins (LDL) on the hydraulic conductivity of Matrigel, a basement membrane matrix. The hydraulic conductivity of Matrigel with latex nanospheres or LDL particles added at 4.8% weight fraction was measured and compared with the hydraulic conductivity of Matrigel alone. The LDL-derived lipids in the gel were visualized by transmission electron microscopy and were seen to have aggregated into particles up to 500 nm in size. The addition of these materials to the medium markedly decreased its hydraulic conductivity, with the LDL-derived lipids having a much larger effect than did the latex nanospheres. Debye-Brinkman theory was used to predict the effect of addition of particles to the hydraulic conductivity of the medium. The theoretical predictions matched well with the results from adding latex nanospheres to the medium. However, LDL decreased hydraulic conductivity much more than was predicted by the theory. The validation of the theoretical model for rigid particles embedded in extracellular matrix suggests that it could be used to make predictions about the influence of particulates (e.g., collagen, elastin, cells) on the hydraulic conductivity of the fine filamentous matrix (the proteoglycans) in connective tissues. In addition, the larger-than-predicted effects of lipidlike particles on hydraulic conductivity may magnify the pathology associated with lipid accumulation, such as in Bruch's membrane of the retina during macular degeneration and the blood vessel wall in atherosclerosis.

Sign in / Sign up

Export Citation Format

Share Document