scholarly journals In-Situ Helium Implantation and TEM Investigation of Radiation Tolerance to Helium Bubble Damage in Equiaxed Nanocrystalline Tungsten and Ultrafine Tungsten-TiC Alloy

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 794 ◽  
Author(s):  
Osman El Atwani ◽  
Kaan Unal ◽  
William Streit Cunningham ◽  
Saryu Fensin ◽  
Jonathan Hinks ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Bubble Formation ◽  
Coarse Grained ◽  
Irradiation Damage ◽  
Radiation Tolerance ◽  
Helium Bubble ◽  
Average Grain Size ◽  
Order Of Magnitude ◽  
Helium Implantation

The use of ultrafine and nanocrystalline materials is a proposed pathway to mitigate irradiation damage in nuclear fusion components. Here, we examine the radiation tolerance of helium bubble formation in 85 nm (average grain size) nanocrystalline-equiaxed-grained tungsten and an ultrafine tungsten-TiC alloy under extreme low energy helium implantation at 1223 K via in-situ transmission electron microscope (TEM). Helium bubble damage evolution in terms of number density, size, and total volume contribution to grain matrices has been determined as a function of He+ implantation fluence. The outputs were compared to previously published results on severe plastically deformed (SPD) tungsten implanted under the same conditions. Large helium bubbles were formed on the grain boundaries and helium bubble damage evolution profiles are shown to differ among the different materials with less overall damage in the nanocrystalline tungsten. Compared to previous works, the results in this work indicate that the nanocrystalline tungsten should possess a fuzz formation threshold more than one order of magnitude higher than coarse-grained tungsten.

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 Helium bubble formation in nuclear glass by in-situ TEM ion implantation

2014 ◽  
Vol 452 (1-3) ◽  
pp. 565-568 ◽  
Author(s):  
G. Gutierrez ◽  
S. Peuget ◽  
J.A. Hinks ◽  
G. Greaves ◽  
S.E. Donnelly ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Bubble Formation ◽  
In Situ Tem ◽  
Helium Bubble

Helium-bubble formation behavior of SiCf/SiC composites after helium implantation

1999 ◽  
Vol 264 (3) ◽  
pp. 355-358 ◽  
Author(s):  
A Hasegawa ◽  
M Saito ◽  
S Nogami ◽  
K Abe ◽  
R.H Jones ◽  
...  
Keyword(s):  
Bubble Formation ◽  
Helium Bubble ◽  
Formation Behavior ◽  
Helium Implantation ◽  
Sic Composites

Synthesis and Ionic Conductivity of Nanophase Ca1-xLaxF2+x

1992 ◽  
Vol 286 ◽  
Author(s):  
Xijun Wu ◽  
Fang Su ◽  
Xiaoying Qin ◽  
Bin Xie ◽  
Xiaoli Ji
Keyword(s):  
Ionic Conductivity ◽  
Volume Fraction ◽  
Complex Impedance ◽  
Ionic Conductors ◽  
Gas Condensation ◽  
Large Volume Fraction ◽  
Average Grain Size ◽  
Order Of Magnitude ◽  
Compacting Pressure

ABSTRACTThe nanophase ionic conductors Ca1-xLaxF2+x with x=0 and 0.25 were synthesized by an inert gas condensation and in situ compacting technique. The samples with average grain size of 16 na for nanophase CaF2 and 11 nm for nanophase Ca0.75 La0.25F2.25 were prepared under the compacting pressure of 0.5 GPa. The alternating ionic conductivity was deduced from the temperature dependence of the complex impedance.The results indicated that the logarithm of ionic conductivity obeys Arrhenius relation in the temperature range from 300 °C to 530 °C both for nanophase CaF2 and for nanophase Ca0.75La0.25F2.25. Their activation energies are 1.14 eV and 1.00 eV, respectively. The ionic conductivity of nanophase CaF2 is about one and two orders of magnitude higher than that of polycrystalline and single crystal CaF2, respectively. While the ionic conductivity of nanophase Ca0.75La0.25F2.25 is about one order of magnitude higher than that of nanophase CaF2. Further analysis indicated that the enhanced ionic conductivity of nanophase Ca1-xLaxF2+x is related to the large volume fraction of interfaces.

In situ irradiation effects studies in medium- and high-voltage TEM

1995 ◽  
Vol 53 ◽  
pp. 234-235
Author(s):  
Charles W. Allen
Keyword(s):  
Cross Section ◽  
Particle Flux ◽  
Threshold Value ◽  
High Energy ◽  
Irradiation Damage ◽  
Defect Complexes ◽  
Lattice Position ◽  
Electrons And Ions ◽  
The Masses

With respect to structural consequences within a material, energetic electrons, above a threshold value of energy characteristic of a particular material, produce vacancy-interstial pairs (Frenkel pairs) by displacement of individual atoms, as illustrated for several materials in Table 1. Ion projectiles produce cascades of Frenkel pairs. Such displacement cascades result from high energy primary knock-on atoms which produce many secondary defects. These defects rearrange to form a variety of defect complexes on the time scale of tens of picoseconds following the primary displacement. A convenient measure of the extent of irradiation damage, both for electrons and ions, is the number of displacements per atom (dpa). 1 dpa means, on average, each atom in the irradiated region of material has been displaced once from its original lattice position. Displacement rate (dpa/s) is proportional to particle flux (cm-2s-1), the proportionality factor being the “displacement cross-section” σD (cm2). The cross-section σD depends mainly on the masses of target and projectile and on the kinetic energy of the projectile particle.

A Study of Electron Beam Irradiation Influence on Device Contact Junction Characteristics of Advanced DRAM Using Atomic Force Probing

2013 ◽  
Author(s):  
Wei-Chih Wang ◽  
Jian-Shing Luo
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Forward Bias ◽  
Irradiation Damage ◽  
Beam Irradiation ◽  
Excess Current ◽  
Atomic Force ◽  
Order Of Magnitude ◽  
Voltage Contrast ◽  
Acceleration Voltage

Abstract In this paper, we revealed p+/n-well and n+/p-well junction characteristic changes caused by electron beam (EB) irradiation. Most importantly, we found a device contact side junction characteristic is relatively sensitive to EB irradiation than its whole device characteristic; an order of magnitude excess current appears at low forward bias region after 1kV EB acceleration voltage irradiation (Vacc). Furthermore, these changes were well interpreted by our Monte Carlo simulation results, the Shockley-Read Hall (SRH) model and the Generation-Recombination (G-R) center trap theory. In addition, four essential examining items were suggested and proposed for EB irradiation damage origins investigation and evaluation. Finally, by taking advantage of the excess current phenomenon, a scanning electron microscope (SEM) passive voltage contrast (PVC) fault localization application at n-FET region was also demonstrated.

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.

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