Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

Heavy Ion ◽

High Energy ◽

Mechanical Twinning ◽

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

Radiation-induced disordering and amorphization—An in situ HVEM study of uranium silicide with comparison to natural processes in zirconolite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175806 ◽

1990 ◽

Vol 48 (4) ◽

pp. 534-535

Author(s):

R. C. Birtcher ◽

L. M. Wang ◽

C. W. Allen ◽

R. C. Ewing

Keyword(s):

Electron Irradiation ◽

Ion Irradiation ◽

Ion Beam ◽

National Laboratory ◽

Heavy Ion ◽

High Energy ◽

In Situ Tem ◽

We present here results of in situ TEM diffraction observations of the response of U3Si and U3Si2 when subjected to 1 MeV electron irradiation or to 1.5 MeV Kr ion irradiation, and observations of damage occuring in natural zirconolite. High energy electron irradiation or energetic heavy ion irradiation were performed in situ at the HVEM-Tandem User Facility at Argonne National Laboratory. In this Facility, a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter have been interfaced to a 1.2 MeV AEI high voltage electron microscope. This allows a wide variety of in situ experiments to be performed with simultaneous ion irradiation and conventional transmission electron microscopy. During the electron irradiation, the electron beam was focused to a diameter of about 2 μ.m at the specimen thin area. The ion beam was approximately 2 mm in diameter and was uniform over the entire specimen. With the specimen mounted in a heating holder, the temperature increase indicated by the furnace thermocouple during the ion irradiation was typically 8 °K.

Irradiation-induced grain growth in gold and copper: In situ HVEM studies at 75-300 K

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155190 ◽

1989 ◽

Vol 47 ◽

pp. 644-645

Author(s):

Charles W. Allen

Keyword(s):

Grain Growth ◽

Ion Irradiation ◽

Boundary Migration ◽

Ion Beam ◽

National Laboratory ◽

Average Grain Size ◽

Growth Phenomenon ◽

When thin polycrystalline films of Au, Cu and various other materials are subjected to energetic ion irradiation, the average grain size increases even at cryogenic temperatures. As is the case with many ion beam processes, this phenomenon of ion irradiation induced grain growth exhibits only a very mild temperature dependence. This contribution is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction. A series of in situ ion and/or electron irradiation experiments is being performed at the HVEM-Tandem Facility at Argonne which have shown clearly for fine grained Au films that two mechanisms for growth are operative for the ion beam case: grain boundary migration as in normal thermal grain growth and grain coalescence which is similar in appearance to recrystallization by subgrain coalescence. Especially in the case of Au for which ion-induced growth is relatively rapid, such in situ experiments also demonstrate the importance of dislocation activity which is a consequence of the collision cascade damage associated with ion irradiation. Existing theories for irradiation-induced grain growth assume that growth occurs by boundary migration and that only point defects generated at grain boundaries are responsible for the growth phenomenon.

Amorphization Kinetics of Zr (Cr,Fe)2 Under Ion Irradiation

MRS Proceedings ◽

10.1557/proc-279-517 ◽

1992 ◽

Vol 279 ◽

Cited By ~ 4

Author(s):

A. T. Motta ◽

L. M. Howe ◽

P. R. Okamoto

Keyword(s):

Neutron Irradiation ◽

Ion Irradiation ◽

Ion Beam ◽

National Laboratory ◽

Matrix Interface ◽

Thin Foils ◽

Intermetallic Precipitates ◽

Kinetics Of

ABSTRACTThin foils of Zircaloy-4 were irradiated with 350 KeV 40Ar ions in the dual ion beam/HVEM facility at Argonne National Laboratory at 300 – 650 K. The irradiation-induced araorphization of the intermetallic precipitates Zr (Cr, Fe)2 and Zr2 (Ni, Fe) was studied in situ. For Zr (Cr,Fe)2 precipitates the dose-to-amorphization was found to increase exponentially with temperature, with a critical temperature of about 650 K. The amorphization morphology was shown to be homogeneous, with no preferential site for nucleation, in contrast to neutron-irradiation amorphization which started at the precipitate-matrix interface. For Zr2 (Ni,Fe) precipitates it was found that amorphization occurred at 550 K and 600 K, whereas in neutron irradiation no amorphization has been observed at those temperatures. The results are discussed in the context of the previous experimental results of neutron and electron irradiation and likely amorphization mechanisms are proposed.

Characterization of Collision Cascade Damage in Ca2La8(SiO4)6O2 by Hrtem

MRS Proceedings ◽

10.1557/proc-373-389 ◽

1994 ◽

Vol 373 ◽

Cited By ~ 4

Author(s):

L.M. Wang ◽

W.J. Webert

Keyword(s):

Elevated Temperatures ◽

Ion Beam ◽

National Laboratory ◽

Sample Surface ◽

Thermal Recovery ◽

Collision Cascade ◽

Cascade Damage

AbstractCa2La8(SiO4)6O2 thin crystals become amorphous under ion beam irradiation. The ion dose required for complete amorphization of the thin crystal (critical amorphization dose, Dc) increased with the increasing irradiation temperature and decreased with ion mass at elevated temperatures. Samples irradiated with 1-1.5 MeV Ar+, Kr+ and Xe+ ions to doses much lower than Dc, in the temperature range from 20 to 498 K were used for a detailed HRTEM investigation to study the amorphization process. The residual collision cascade damage after irradiation appeared as nanometer scale amorphous domains. The images of these domains are extremely sensitive to the sample thickness. Small domains of cascade size were found only at the very thin edge of the sample. In thicker regions, amorphous domains appear after higher doses as the result of cascade overlap in projection. At higher temperatures, the observed amorphous domains are smaller indicating thermal recovery at the amorphous/crystalline interface. The amorphous domains are also larger in size after irradiation with ions of higher mass at a fixed ion dose. These results are consistent with the Dc-temperature curves determined by in situ TEM with the HVEM-Tandem Facility at Argonne National Laboratory. The width of the amorphous rim along the edge of the specimen grew with increasing ion dose suggesting that amorphization also proceeds from the sample surface. Images of the collision cascade damage were compared to the cascade sizes calculated with the TRIM code. Some digitally acquired HRTEM images of the cascade damage were processed to reveal more detailed information.

The HVEM-tandem user facility at Argonne National Laboratory

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106090 ◽

1988 ◽

Vol 46 ◽

pp. 806-807

Author(s):

C. W. Allen ◽

E. A. Ryan ◽

S. T. Ockers

Keyword(s):

Radiation Effects ◽

Ion Irradiation ◽

Noble Gas ◽

National Laboratory ◽

Western Hemisphere ◽

Accelerator Facility ◽

Wide Range ◽

Established in 1981, the High Voltage Electron Microscope-Tandem Ion Accelerator Facility (HVEM-Tandem) is a user-oriented resource for materials research. It is located at Argonne National Laboratory about 20 miles south of O'Hare International Airport near Chicago. The Facility consists of a modified Kratos/AEI HVEM with accelerating voltages ranging continuously from 0.1-1.2 MeV, interfaced to a 2 MV tandem and a 0.65 MV ion implanter-type accelerator. This combination of instruments offers capability, unique in the western hemisphere, for a wide range of in Situ experiments involving ion irradiation and ion implantation with simultaneous microscopy. During 1987 approximately 75% of microscope time was devoted to this type of experiment (Fig. 1) including studies of solid state phase transformations, such as amorphization, radiation damage and defect structures and the implantation of noble gas and metal ions.In situ experiments of various types account for nearly 90% of usage of the HVEM. In addition to the radiation effects studies, this includes experiments performed in the microscope involving deformation, annealing and environmental effects.

Bubble Formation in Zr Alloys Under Heavy Ion Implantation

MRS Proceedings ◽

10.1557/proc-398-201 ◽

1995 ◽

Vol 398 ◽

Cited By ~ 1

Author(s):

Luciano Pagano ◽

Arthur T. Motta ◽

Robert C. Birtcher

Keyword(s):

Ion Irradiation ◽

National Laboratory ◽

Bubble Formation ◽

Thin Foil ◽

Heavy Ion ◽

Thin Foils ◽

Small Bubbles ◽

Zr Alloys

ABSTRACTWe report here the results of a study conducted to examine the effect of Kr ion irradiation on bubble formation in Zr alloys. We used the HVEM/Tandem facility at Argonne National Laboratory to irradiate several Zr alloys, including Zircaloy-2 and Zircaloy-4, at temperatures from 300 to 800 C and to doses up to 2 × 1016ion.cm−2. Both in-situ irradiation of thin foils as well as irradiation of bulk samples with an ion implanter were used in this study. For the thin foil irradiations, a distribution of small bubbles in the range of 30-100 Å was found, at all temperatures with the exception of the Cr-rich Valloy where bubbles of 130 Å were found. The irradiation of bulk samples at high temperature (700–800 C) produced large faceted bubbles (up to 300 Å) after irradiation to 2 × 1016ion.cm−2. The results are examined in the context of existing models for bubble formation and growth in other metals.

Ion Irradiation of Ternary Pyrochlores

MRS Proceedings ◽

10.1557/proc-1122-o08-03 ◽

2008 ◽

Vol 1122 ◽

Author(s):

Karl R. Whittle ◽

Katherine L. Smith ◽

Mark G. Blackford ◽

Simon A.T. Redfern ◽

Elizabeth J. Harvey ◽

...

Keyword(s):

Ion Irradiation ◽

National Laboratory ◽

Structural Disorder ◽

Critical Temperatures ◽

High Doses

AbstractSynthetic pyrochlore samples Y2Ti2-xSnxO7 (x=0.4, 0.8, 1.2, 1.6), Nd2Zr2O7, Nd2Zr1.2Ti0.8O7, and La1.6Y0.4Hf2O7, were irradiated in-situ using the IVEM-TANDEM microscope facility at the Argonne National Laboratory. The critical temperatures for amorphisation have revealed a dramatic increase in tolerance with increasing Sn content for the Y2Ti2-xSnxO7 series. This change has also found to be linear with increasing Sn content. Nd2Zr1.2Ti0.8O7 and La1.6Y0.4Hf2O7 were both found to amorphise, while Nd2Zr2O7 was found to be stable to high doses (2.5×10^15 ions cm-2). The observed results are presented with respect to previously published results for irradiation stability predictions and structural disorder.

In Situ TEM Observations of Heavy Ion Damage in Gallium Arsenide

MRS Proceedings ◽

10.1557/proc-100-293 ◽

1988 ◽

Vol 100 ◽

Cited By ~ 4

Author(s):

M. W. Bench ◽

I. M. Robertson ◽

M. A. Kirk

Keyword(s):

Low Temperature ◽

Room Temperature ◽

National Laboratory ◽

Heavy Ion ◽

In Situ Tem ◽

Accelerator Facility ◽

Transmission Electron ◽

Ion Accelerator

ABSTRACTTransmission electron microscopy experiments have been performed to investigate the lattice damage created by heavy-ion bombardments in GaAs. These experiments have been performed in situ by using the HVEN - Ion Accelerator Facility at Argonne National Laboratory. The ion bcorbardments (50 keV Ar+ and Kr+) and the microscopy have been carried out at temperatures rangrin from 30 to 300 K. Ion fluences ranged from 2 × 1011 to 5 × 1013 ions cm−2.Direct-inpact amorphization is observed to occur in both n-type and semi-insulating GaAs irradiated to low ion doses at 30 K and room temperature. The probability of forming a visible defect is higher for low temperature irradiations than for room temperature irradiations. The amorphous zones formed at low temperature are stable to temperatures above 250 K. Post implantation annealing is seen to occur at room temperature for all samples irradiated to low doses until eventually all visible damage disappears.

The local structure of Ta(v) aqua ions in high temperature fluoride- and chloride-bearing solutions: Implications for Ta transport in granite-related postmagmatic fluids

The Canadian Mineralogist ◽

10.3749/canmin.1900022 ◽

2019 ◽

Vol 57 (6) ◽

pp. 843-851

Author(s):

Alan J. Anderson ◽

Robert A. Mayanovic ◽

Thomas Lee

Keyword(s):

High Temperature ◽

Local Structure ◽

Elevated Temperatures ◽

National Laboratory ◽

Acidic Solutions ◽

Diamond Anvil ◽

X Ray Absorption ◽

Photon Source

Abstract The local structure of Ta(V) in high-temperature fluoride- and chloride-bearing acidic solutions was investigated using in situ X-ray absorption spectroscopy (XAS). All XAS spectra were collected from two solutions, designated A and B, at beamline ID-20-C at the Advanced Photon Source, Argonne National Laboratory. Spectra were collected from solution A at 350 and 400 °C and from solution B at 25, 360, and 400 °C after the solutions were sealed in a hydrothermal diamond anvil cell. Solution A was prepared by dissolving Ta2O5 powder in 5% HF solution; solution B consisted of TaCl5 dissolved in 2% HF. The dominant tantalum species in solution A at elevated temperatures was TaF83–. In contrast, TaCl6–, which was the dominant complex in solution B at room temperature, disappeared as hydroxide complexes with an average ligand number between 5 and 7 became the dominant species at 350 and 400 °C. The XAS results confirm the previously recognized effect of fluoride activity on Ta speciation in hydrothermal fluids and suggest that both fluoride and hydroxide complexes play an important role in the transport of Ta in acidic fluoride-bearing solutions involved in the formation of mineralized mica-rich replacement units in granitic pegmatites.

In Situ Ion Beam Research In Argonne's Intermediate Voltage Electron Microscope

MRS Proceedings ◽

10.1557/proc-439-277 ◽

1996 ◽

Vol 439 ◽

Cited By ~ 17

Author(s):

Charles W. Allen ◽

Edward A. Ryan

Keyword(s):

Electron Microscope ◽

Ion Irradiation ◽

Noble Gas ◽

Ion Beam ◽

Voltage Electron ◽

In Situ Experiments ◽

User Facility ◽

New Instrumentation ◽

Electron Microscopes

AbstractSince Fall 1995, a state-of-the-art intermediate voltage electron microscope (IVEM) has been operational in the HVEM-Tandem Facility with in situ ion irradiation capabilities similar to those of the HVEM of the Facility. A 300 kV Hitachi H-9000NAR is interfaced to the two ion accelerators of the Facility, with a demonstrated point-topoint spatial resolution for imaging of 0.25 nm with the ion beamline attached to the microscope. The IVEM incorporates a Faraday cup system for ion dosimetry with measurement aperture 6.5 cm from the TEM specimen, which was described in Symposium A of the 1995 MRS Fall Meeting. The IVEM is now employed for a variety of in situ ion beam studies ranging from low dose ion damage experiments with GaAs, in which damage zones individual displacement cascades are observed, to implantation studies in metals, in which irradiation-induced noble gas precipitate mobility is studied in real time. In this presentation, the new instrumentation and its specifications will be described briefly, several basic concepts relating to in situ experiments in transmission electron microscopes will be summarized and examples of in situ experiments will be presented which exploit the experimental capabilities of this new user facility instrumentation.