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

1992 ◽  
Vol 279 ◽  
Author(s):  
A. T. Motta ◽  
L. M. Howe ◽  
P. R. Okamoto
Keyword(s):  
Neutron Irradiation ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne 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.

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

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

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

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 ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
In Situ Tem ◽  
In Situ Experiments

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.

scholarly journals In-situ annealing of self-ion irradiation damage in tungsten

2014 ◽  
Vol 1712 ◽  
Author(s):  
Xiaoou. Yi ◽  
Michael L. Jenkins ◽  
Steve G. Roberts ◽  
Marquis A. Kirk
Keyword(s):  
Ion Irradiation ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Irradiation Damage ◽  
Dislocation Loops ◽  
Thin Foils ◽  
Defect Mobility ◽  
Increasing Temperature ◽  
Thermal Stability Of

ABSTRACTIn our earlier work [1] microstructural evolution in tungsten under self-ion irradiation was investigated as a function of temperature and dose by in-situ 150 keV W+ ion irradiations on the IVEM-Tandem facility at Argonne National Laboratory (ANL). The present work focuses on the thermal stability of this damage. Thin foils of tungsten were irradiated at room temperature (R.T.) to fluences up to 1018 W+m-2 (∼ 1.0 dpa) and were then annealed in-situ for up to 120 min at temperatures between 300 and 800°C.We found that: (1) loops with Burgers vectors ½ <111> and <100> coexist during annealing; (2) <100> is not a stable loop configuration above 300°C and the fraction of such loops decreased with increasing temperature and/or time; (3) changes in loop populations during annealing were very sensitive to temperature, but less sensitive to time. The majority of changes occurred within 15 min, and were associated with the loss of small (1-2 nm) dislocation loops. The origin of these trends is discussed by considering defect mobility and the energetics of defect configurations predicted by previous DFT calculations [2].

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

1989 ◽  
Vol 47 ◽  
pp. 644-645
Author(s):  
Charles W. Allen
Keyword(s):  
Grain Growth ◽  
Ion Irradiation ◽  
Boundary Migration ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Average Grain Size ◽  
Growth Phenomenon ◽  
In Situ Experiments

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.

scholarly journals Bubble Formation in Zr Alloys Under Heavy Ion Implantation

1995 ◽  
Vol 398 ◽  
Author(s):  
Luciano Pagano ◽  
Arthur T. Motta ◽  
Robert C. Birtcher
Keyword(s):  
Ion Irradiation ◽  
National Laboratory ◽  
Bubble Formation ◽  
Argonne National Laboratory ◽  
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

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 ◽  
Argonne 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.

Crystallization of nano-size thallous oxide during ion irradiation of Tl-Ba-Ca-Cu-O high-temperature superconductors

1995 ◽  
Vol 53 ◽  
pp. 214-215
Author(s):  
P. P. Newcomer ◽  
L. M. Wang ◽  
M. L. Miller ◽  
R. C. Ewing
Keyword(s):  
High Temperature ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Temperature Superconductors ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Planetary Science ◽  
University Of New Mexico ◽  
The University ◽  
Nano Size

The Tl-Ba-Ca-Cu-O class of type-II high temperature superconductors (HTS) have Tc's as high as 125K. Although they have good critical current values, when a field is applied the weak pinning and consequent flow of magnetic vortices are a major impediment to the usefulness of these materials. Ion irradiation has been shown to enhance the pinning. High quality single crystals, as determined with x-ray precession and HRTEM, with sharp HTS Meissner signals, were irradiated with 1.5 MeV Kr+ and Xe+ ions using the HVEM-Tandem facility at Argonne National Laboratory. Ion beam microstructural modification was studied in-situ using electron diffraction and after irradiation using HRTEM and nano-beam EDS on Tl-1212 and Tl-2212 (numbers designate the stoichiometry Tl-Ba- Ca-Cu-O) single-crystal HTS. After irradiation, microstructure was studied using the JEOL 2010 in the Earth and Planetary Science Department at the University of New Mexico in order to characterize the resulting irradiation-induced nano-size precipitates.

In sito Ion Beam Analysis of Radiation Damage Kinetics in MgTiO3 Single Crystals at 170-470 K

1995 ◽  
Vol 396 ◽  
Author(s):  
Ning Yu ◽  
Jeremy N. Mitchell ◽  
Kurt E. Sickafus ◽  
Michael Nastasi
Keyword(s):  
Radiation Damage ◽  
Single Crystals ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Los Alamos National Laboratory ◽  
Beam Analysis ◽  
Radiation Resistant ◽  
Threshold Doses

AbstractRadiation damage kinetics in synthetic MgTiO3 (geikielite) single crystals have been studied using the in situ ion beam facility at Los Alamos National Laboratory. The geikielite samples were irradiated at temperatures of 170, 300, and 470 K with 400 keV xenon ions and the radiation damage was sequentially measured with Rutherford backscattering using a 2 MeV He ion beam along a channeling direction. Threshold doses of 1 and 5×1015 Xe/cm2 were determined for the crystalline-to-amorphous transformation induced by Xe ion irradiation at 170 and 300 K, respectively. However, geikielite retained its crystallinity up to a dose of 2.5x1016 Xe/cm2 at the irradiation temperature of 470 K. This study has shown that MgTiO3, which has a corundum derivative structure, is another radiation resistant material that has the potential for use in radiation environments.

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

1994 ◽  
Vol 373 ◽  
Author(s):  
L.M. Wang ◽  
W.J. Webert
Keyword(s):  
Elevated Temperatures ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne 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.

Ion-Beam Amortization of Ca2La2(SiO4)6O2 Single Crystals

1992 ◽  
Vol 279 ◽  
Author(s):  
William J. Weber ◽  
Lu-Min Wang
Keyword(s):  
Electron Microscopy ◽  
Single Crystals ◽  
Structural Changes ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Annealing Process ◽  
Recoil Energy ◽  
Transmission Electron

ABSTRACTSingle crystals of Ca2La8(SiO4)6O2 were irradiated with 1.5 MeV Xe+, 1.5 MeV Kr+, 1.0 MeV Ar+ and 0.8 MeV Ne+ ions to investigate the effects of recoil-energy spectrum, temperature, and crystallographic orientation on irradiation-induced amorphization. The irradiations were carried out using the HVEM-Tandem Facility at Argonne National Laboratory. The structural changes and the ion fluence for complete amorphization in the electron transparent thickness of the specimens were determined by in situ transmission electron microscopy. The displacement dose determined for complete amorphization was approximately 0.6 dpa for the Xe+, Kr+, and Ar+ ion irradiations but increased to 1.4 dpa for the Ne+ ion irradiations, which may reflect an effect of lower recoil energies. The ion fluence for complete amorphization increased exponentially with temperature over the range from 25 to 400°C. Amorphization was not observed at 500°C. The activation energy associated with this simultaneous annealing process was estimated to be 0.13 eV, and the critical amorphization temperature was estimated to be 438°C for the 1.5 MeV Kr+ irradiations.

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