scholarly journals Ion Irradiation-Induced Microstructural Evolution of Ni–Mo–Cr Low Alloy Steels

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2268
Author(s):  
Hongying Sun ◽  
Penghui Lei ◽  
Guang Ran ◽  
Hui Wang ◽  
Jiyun Zheng ◽  
...  
Keyword(s):  
Irradiation Dose ◽  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Strength ◽  
Positron Annihilation Spectroscopy ◽  
Small Scale ◽  
Low Alloy Steels ◽  
Dislocation Loops ◽  
S Parameter

As leading candidates of sheet steels for advanced nuclear reactors, three types of Ni–Mo–Cr high-strength low alloy (HSLA) steels named as CNST1, CNST2 and CNSS3 were irradiated by 400 keV Fe+ with peak fluence to 1.4 × 1014, 3.5 × 1014 and 7.0 × 1014 ions/cm2, respectively. The distribution and morphology of the defects induced by the sample preparation method and Fe+ irradiation dose were investigated by transmission electron microscopy (TEM) and positron-annihilation spectroscopy (PAS). TEM samples were prepared with two methods, i.e., a focused ion beam (FIB) technique and the electroplating and twin-jet electropolishing (ETE) method. Point defects and dislocation loops were observed in CNST1, CNST2 and CNSS3 samples prepared via FIB. On the other hand, samples prepared via the ETE method revealed that a smaller number of defects was observed in CNST1, CNST2 and almost no defects were observed in CNST3. It is indicated that artifact defects could be introduced by FIB preparation. The PAS S-W plots showed that the existence of two types of defects after ion implantation included small-scale defects such as vacancies, vacancy clusters, dislocation loops and large-sized defects. The S parameter of irradiated steels showed a clear saturation in PAS response with increasing Fe+ dose. At the same irradiation dose, higher values of the S-parameter were achieved in CNST1 and CNST2 samples when compared to that in CNSS3 samples. The mechanism and evolution behavior of irradiation-induced defects were analyzed and discussed.

scholarly journals Effect of Ion Irradiation on Nanoindentation Fracture and Deformation in Silicon Carbide

JOM ◽  
2021 ◽  
Author(s):  
Alexander J. Leide ◽  
Richard I. Todd ◽  
David E. J. Armstrong
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Residual Stresses ◽  
Focused Ion Beam ◽  
Electron Backscatter Diffraction ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Resolution Electron ◽  
Radiation Induced ◽  
Compressive Residual Stresses

AbstractSilicon carbide is desirable for many nuclear applications, making it necessary to understand how it deforms after irradiation. Ion implantation combined with nanoindentation is commonly used to measure radiation-induced changes to mechanical properties; hardness and modulus can be calculated from load–displacement curves, and fracture toughness can be estimated from surface crack lengths. Further insight into indentation deformation and fracture is required to understand the observed changes to mechanical properties caused by irradiation. This paper investigates indentation deformation using high-resolution electron backscatter diffraction (HR-EBSD) and Raman spectroscopy. Significant differences exist after irradiation: fracture is suppressed by swelling-induced compressive residual stresses, and the plastically deformed region extends further from the indentation. During focused ion beam cross-sectioning, indentation cracks grow, and residual stresses are modified. The results clarify the mechanisms responsible for the modification of apparent hardness and apparent indentation toughness values caused by the compressive residual stresses in ion-implanted specimens.

A Method for Site Specific Characterization Using a Dedicated FIB System Combined With an Analyitical TEM

1999 ◽  
Vol 5 (S2) ◽  
pp. 914-915
Author(s):  
T. Kamino ◽  
T. Yaguchi ◽  
H. Matsumoto ◽  
H. Kobayashi ◽  
H. Koike
Keyword(s):  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
System Stability ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Cross Sectional ◽  
Site Specific ◽  
Specimen Holder ◽  
High Resolution Tem

A method for site specific characterization of the materials using a dedicated focused ion beam(FIB) system and an analytical transmission electron microscope (TEM) was developed. Needless to say, in TEM specimen preparation using FIB system, stability of a specimen is quite important. The specimen stage employed in the developed FIB system is the one designed for high resolution TEM, and the specimen drift rate of the stage is less than lnm/min. In addition, FIB-TEM compatible specimen holder which allows milling of a specimen with the FIB system and observation of the specimen with the TEM without re-loading was developed. To obtain thin specimen from the area to be characterized correctly, confirmation of the area before final milling is needed. However, observation of cross sectional view in a FIB system is recommended because it causes damage by Ga ion irradiation. To solve this problem, we used a STEM unit as a viewer of FIB milled specimen.

scholarly journals Optimization of Pt-C Deposits by Cryo-FIBID: Substantial Growth Rate Increase and Quasi-Metallic Behaviour

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1906 ◽  
Author(s):  
Alba Salvador-Porroche ◽  
Soraya Sangiao ◽  
Patrick Philipp ◽  
Pilar Cea ◽  
José María De Teresa
Keyword(s):  
Growth Rate ◽  
Electrical Resistivity ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Electrical Contacts ◽  
Condensation Temperature ◽  
Monte Carlo Code ◽  
Condensed Layer

The Focused Ion Beam Induced Deposition (FIBID) under cryogenic conditions (Cryo-FIBID) technique is based on obtaining a condensed layer of precursor molecules by cooling the substrate below the condensation temperature of the gaseous precursor material. This condensed layer is irradiated with ions according to a desired pattern and, subsequently, the substrate is heated above the precursor condensation temperature, revealing the deposits with the shape of the exposed pattern. In this contribution, the fast growth of Pt-C deposits by Cryo-FIBID is demonstrated. Here, we optimize various parameters of the process in order to obtain deposits with the lowest-possible electrical resistivity. Optimized ~30 nm-thick Pt-C deposits are obtained using ion irradiation area dose of 120 μC/cm2 at 30 kV. This finding represents a substantial increment in the growth rate when it is compared with deposits of the same thickness fabricated by standard FIBID at room temperature (40 times enhancement). The value of the electrical resistivity in optimized deposits (~4 × 104 µΩ cm) is suitable to perform electrical contacts to certain materials. As a proof of concept of the potential applications of this technology, a 100 µm × 100 µm pattern is carried out in only 43 s of ion exposure (area dose of 23 μC/cm2), to be compared with 2.5 h if grown by standard FIBID at room temperature. The ion trajectories and the deposit composition have been simulated using a binary-collision-approximation Monte Carlo code, providing a solid basis for the understanding of the experimental results.

scholarly journals The Effect of Internal Free Surfaces on Void Swelling of Irradiated Pure Iron Containing Subsurface Trenches

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 252
Author(s):  
Tianyao Wang ◽  
Hyosim Kim ◽  
Frank A. Garner ◽  
Kenneth L. Peddicord ◽  
Lin Shao
Keyword(s):  
Pure Iron ◽  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Full Range ◽  
Peak Displacement ◽  
Free Surfaces ◽  
Projected Range ◽  
Void Swelling ◽  
Displacement Per Atom

We studied the effects of internal free surfaces on the evolution of ion-induced void swelling in pure iron. The study was initially driven by the motivation to introduce a planar free-surface defect sink at depths that would remove the injected interstitial effect from ion irradiation, possibly enhancing swelling. Using the focused ion beam technique, deep trenches were created on a cross section of pure iron at various depths, so as to create bridges of thickness ranging from 0.88 μm to 1.70 μm. Samples were then irradiated with 3.5 MeV Fe2+ ions at 475 °C to a fluence corresponding to a peak displacement per atom dose of 150 dpa. The projected range of 3.5 MeV Fe2+ ions is about 1.2 μm so the chosen bridge thicknesses involved fractions of the ion range, thicknesses comparable to the mean ion range (peak of injected interstitial distribution), and thicknesses beyond the full range. It was found that introduction of such surfaces did not enhance swelling but actually decreased it, primarily because there were now two denuded zones with a combined stronger influence than that of the injected interstitial. The study suggests that such strong surface effects must be considered for ion irradiation studies of thin films or bridge-like structures.

scholarly journals Low-temperature rheology of calcite

2019 ◽  
Vol 221 (1) ◽  
pp. 129-141 ◽  
Author(s):  
Michael K Sly ◽  
Arashdeep S Thind ◽  
Rohan Mishra ◽  
Katharine M Flores ◽  
Philip Skemer
Keyword(s):  
Low Temperature ◽  
Yield Stress ◽  
Low Temperatures ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polycrystalline Sample ◽  
Small Scale ◽  
Indentation Hardness ◽  
Micropillar Compression ◽  
Flow Laws

SUMMARY Low-temperature plastic rheology of calcite plays a significant role in the dynamics of Earth's crust. However, it is technically challenging to study plastic rheology at low temperatures because of the high confining pressures required to inhibit fracturing. Micromechanical tests, such as nanoindentation and micropillar compression, can provide insight into plastic rheology under these conditions because, due to the small scale, plastic deformation can be achieved at low temperatures without the need for secondary confinement. In this study, nanoindentation and micropillar compression experiments were performed on oriented grains within a polycrystalline sample of Carrara marble at temperatures ranging from 23 to 175 °C, using a nanoindenter. Indentation hardness is acquired directly from nanoindentation experiments. These data are then used to calculate yield stress as a function of temperature using numerical approaches that model the stress state under the indenter. Indentation data are complemented by uniaxial micropillar compression experiments. Cylindrical micropillars ∼1 and ∼3 μm in diameter were fabricated using a focused ion beam-based micromachining technique. Yield stress in micropillar experiments is determined directly from the applied load and micropillar dimensions. Mechanical data are fit to constitutive flow laws for low-temperature plasticity and compared to extrapolations of similar flow laws from high-temperature experiments. This study also considered the effects of crystallographic orientation on yield stress in calcite. Although there is a clear orientation dependence to plastic yielding, this effect is relatively small in comparison to the influence of temperature.

scholarly journals Effects of the Surface on Displacement Cascades Produced by Heavy-Ion Irradiation of Ni3Al and Cu3Au

1996 ◽  
Vol 439 ◽  
Author(s):  
S. Müller ◽  
M. L. Jenkins ◽  
C. Abromeit ◽  
H. Wollenberger
Keyword(s):  
Ion Irradiation ◽  
Incident Angle ◽  
Ion Beam ◽  
Heavy Ion ◽  
Small Population ◽  
Dislocation Loops ◽  
Near Surface ◽  
Ion Energy ◽  
Heavy Ion Irradiation ◽  
Transmission Electron

AbstractStereo transmission electron microscopy has been used to characterise the distribution in depth of disordered zones and associated dislocation loops in the ordered alloys Ni3Al and Cu3Au after heavy ion irradiation, most extensively for Ni3Al irradiated with 50 keV Ta+ ions at a temperature of 573 K. The Cu3Au specimen was irradiated with 50 keV Ni+ ions at an incident angle of 45° at a temperature of 373 K. In Ni3Al the defect yield, i.e. the probability for a disordered zone to contain a loop was found to be strongly dependent on the depth of the zone in the foil, varying from about 0.7 for near-surface zones to about 0.2 in the bulk. The sizes and shapes of disordered zones were only weakly dependent on depth, except for a small population of zones very near the surface which were strongly elongated parallel to the incident ion beam. In Cu3Au the surface had a smaller but still significant effect on the defect yield. The dependence of the tranverse disordered zone diameter d on ion energy E for Ta+ irradiation of NiA was found to follow a relationship d = k1, E1/α with k, = 2.4 ± 0.4 and α = 3.3 ± 0.4. A similar relationship with the same value of α is valid for a wide variety of incident ion/target combinations found in the literature.

Low Energy Focused Ion Beam Processing

1992 ◽  
Vol 279 ◽  
Author(s):  
Kenji Gamo
Keyword(s):  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Etching Rate ◽  
High Mobility ◽  
Low Energy ◽  
High Electron ◽  
Optimization Of Process Parameters ◽  
High Etching Rate

ABSTRACTFocused ion beam (FIB) techniques have many advantages which stem from being maskless and have attracted much interest for various applications includingin situprocessing. However, reduction of damage and improvement of throughput are problems awaiting solution. For reduction of damage, low energy FIB is promising and for improvement of throughput, understanding of the basic processes and optimization of process parameters based on this understanding is crucial. This paper discusses characteristics of low energy FIB system, ion beam assisted etching and ion implantation, and effect of damage with putting emphasize onin situfabrication. Low energy (0.05–25keV) FIB system being developed forms -lOOnm diameter ion beams and is connected with molecular beam epitaxy system. Many results indicate that low damage, maskless ion beam assisted etching is feasible using low energy beams. Recently it was also shown that for ion beam assisted etching of GaAs, pulse irradiation yields very high etching rate of 500/ion. This indicates that the optimization of the relative ratio of ion irradiation and reactant gas supply as important to achieve high etching rate. Low energy FIB is also important for selective doping for high electron mobility heterostructures of GaAs/GaAlAs, because high mobility is significantly degraded by a slight damage.

scholarly journals Stem-EDX and FIB-SEM Tomography of ALLVAC 718Plus Superalloy

2016 ◽  
Vol 61 (2) ◽  
pp. 535-542 ◽  
Author(s):  
A. Kruk ◽  
G. Cempura ◽  
S. Lech ◽  
A. Czyrska -Filemonowicz
Keyword(s):  
Electron Microscope ◽  
Focused Ion Beam ◽  
Electron Tomography ◽  
Ion Beam ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Scanning Transmission Electron Microscope ◽  
Particle Analysis ◽  
Transmission Electron ◽  
Scanning Transmission

Abstract Allvac 718Plus (718Plus) is a high strength, corrosion resistant nickel- based superalloy used for application in power generation, aeronautics and aerospace industry. The 718Plus microstructure consists of a γ matrix with γ’-Ni3(Al,Ti) and some δ- Ni3Nb phases as well as lamellar particles (η-Ni3Ti, η*-Ni6AlNb or Ni6(Al,Ti)Nb) precipitated at the grain boundaries. The primary strengthening mechanism for this alloy is a precipitation hardening, therefore size and distribution of precipitates are critical for the performance of the alloy. The aim of this study was to characterize precipitates in the 718Plus superalloy using Scanning Transmission Electron Microscope combined with Energy Dispersive X-ray Spectroscopy (STEM-EDX) and Focused Ion Beam Scanning Electron Microscope (FIB-SEM). The STEM-EDX and FIB-SEM tomography techniques were used for 3D imaging and metrology of the precipitates. Transmission electron microscopy and EDX spectroscopy were used to reveal details of the 718Plus microstructure and allow determine chemical composition of the phases. The study showed that electron tomography techniques permit to obtain complementary information about microstructural features (precipitates size, shape and their 3D distribution) in the reconstructed volume with comparison to conventional particle analysis methods, e.g. quantitative TEM and SEM metallography

Experiment Research for Fracture Toughness of PAN-Based Carbon Fibers

2011 ◽  
Vol 462-463 ◽  
pp. 1361-1366 ◽  
Author(s):  
Bo Ming Zhang ◽  
Yu Fen Wu
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Carbon Fibers ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
High Strength ◽  
Carbon Filaments ◽  
Fracture Theory ◽  
In Virtue Of

For the sake of the carbon filaments’ fracture toughness, using the focused ion beam (FIB) to etch the carbon fibers and got different tensile strength, and all specimens were stretched on an Instron-type filaments testing machine and got the samples’ tensile strength, The crack-to-mirror size ratio was assumed as a constant, In virtue of Griffith fracture theory, Fracture toughness (KΙC) of representative high-strength type PAN (polyacrylonitrile)-based carbon fibers, Torayca T300 and T800, were estimated to be 1MPam1/2 from the tensile strength vs. fracture mirror size relation.

Small Scale Plastic Yielding of Mg Alloys Assessed with Nanoindentation

2020 ◽  
Vol 405 ◽  
pp. 339-344
Author(s):  
Jiří Němeček ◽  
Jan Maňák ◽  
Jiří Němeček
Keyword(s):  
Focused Ion Beam ◽  
Electron Backscatter Diffraction ◽  
Ion Beam ◽  
Az31 Alloy ◽  
Small Scale ◽  
Spherical Indentation ◽  
Plastic Properties ◽  
Indentation Tests ◽  
Order Of Magnitude ◽  
Volume Characteristics

The paper investigates deformations and plastic properties received from different material volumes and tests of magnesium samples. Small volume characteristics gained on single Mg crystals are compared to polycrystalline AZ31 alloy. Results of tests employing nanoindentation, focused ion beam milling and electron backscatter diffraction techniques are presented. Large differences were found between micro-beam testing and spherical indentation tests having the volume one order of magnitude apart. The plastic strength scaling factor was found 1.7 for the studied grain configurations and volumes.

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