scholarly journals Phase Transformations In Nickel-Aluminum Alloys During Ion Beam Mixing

1985 ◽  
Vol 51 ◽  
Author(s):  
James Eridon ◽  
Lynn Rehn ◽  
Gary Was
Keyword(s):  
Aluminum Alloys ◽  
Phase Transformations ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Amorphous Structure ◽  
X Rays ◽  
Nickel Aluminum ◽  
Ion Beam Mixing ◽  
Voltage Electron

ABSTRACTThe effect of ion beam mixing of nickel-aluminum alloys with 500 keV krypton ions has been investigated over a range of temperature, composition, ion dose, and post-irradiation thermal treatments. Samples were formed by aternate evaporation of layers of aluminum and nickel. A portion of these samples was subsequently annealed to form intermetallic compunds. Irradiations were performed at both room temperature and 80 K using the 2 MV ion accelerator at Argonne National Laboratory. Phase transformations were observed during both in situ irradiations in the High Voltage Electron Microscope(HVEM) at Argonne and also in subsequent analysis of an array of irradiated samples. Electron diffraction indicates the presence of metastable crystalline structures not present in the conventional nickel-aluminum phase diagram. Transformations occur at doses as low as 5×1014 cm−2 and continue to develop as the irradiation progresses up to 2×l016 cm−2. Layer mixing is followed through Rutherford Backscattering analysis. Samples are also checked with x-rays and Electron Energy Loss Spectroscopy (EELS). A thermodynamic argument is presented to explain the phase transformations in terms of movements on a free energy diagram. This analysis explains the interesting paradox concerning the radiation hardness of the NiAl[l] phase and the amorphous structure of mixed Ni-50% Al layers[2].

Time-resolved studies of the order–disorder phase transformations in rare-earth–transition metal intermetallics with 2-17 stoichiometry

2008 ◽  
Vol 23 (11) ◽  
pp. 2886-2896 ◽  
Author(s):  
Y.Y. Kostogorova-Beller ◽  
M.J. Kramer ◽  
J.E. Shield
Keyword(s):  
Rare Earth ◽  
Phase Transformations ◽  
Rietveld Method ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
High Energy ◽  
Lattice Parameters ◽  
X Rays ◽  
Time Resolved ◽  
Alloying Additions

High-temperature order–disorder transformations in R2T17 and R2T17-M-C intermetallics with R = Pr, Sm, Dy, Tb; T = Co, Fe; and M = Zr, Nb were studied utilizing time-resolved synchrotron x-ray diffraction at the Advanced Photon Source (APS) at the U.S. Department of Energy’s Argonne National Laboratory (Argonne, IL). High-energy synchrotron radiation provides intense, highly penetrating x-rays, which are ideal for in situ studies of phase transformations. Alloying additions are used to stabilize formation of metastable phases; their influence on order recovery was investigated. The experimental setup utilized Debye–Scherrer geometry; specimens were heated at a rate of 10 K/min. Full-profile diffraction patterns collected every 10 s were refined in sequence using the Rietveld method to track changes of lattice parameters and phase assemblages during heating. Sharp changes observed in the evolution of temperature-dependent lattice parameters suggested formation of ordered structure via nucleation and growth. Both 2-17 polymorphs co-existed in light and heavy rare-earth systems at high temperatures. The presence of alloying additions in the solid solution greatly influenced long-range order formation.

scholarly journals Ion-Beam Mixing and Solid-State Reaction in Zr-Fe Multilayers

1996 ◽  
Vol 439 ◽  
Author(s):  
A. Paesano ◽  
A. T. Motta ◽  
R. C. Birtcher ◽  
E. A. Ryan ◽  
S. R. Teixeira ◽  
...  
Keyword(s):  
Solid State ◽  
Amorphous Phase ◽  
Solid State Reaction ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Reaction Products ◽  
Phase Selection ◽  
Voltage Electron ◽  
Multilayered Thin Films

AbstractVapor-deposited Zr-Fe multilayered thin films with various wavelengths and of overall composition either 50% Fe or Fe-rich up to 57 % Fe were either irradiated with 300 keV Kr ions at temperatures from 25K to 623 K to fluences up to 2 × 1016 cm−2, or simply annealed at 773K in-situ in the Intermediate Voltage Electron Microscope at Argonne National Laboratory. Under irradiation, the final reaction product is the amorphous phase in all cases studied, but the dose to amorphization depends on the temperature and on the wavelength. In the purely thermal case (annealing at 773 K), the 50–50 composition produces the amorphous phase but for the Fe-rich multilayers the reaction products depend on the multilayer wavelength. For small wavelength, the amorphous phase is still formed, but at large wavelength the Zr-Fe crystalline intermetallic compounds appear. These results are discussed in terms of existing models of irradiation kinetics and phase selection during solid state reaction.

Ion Beam Irradiation of Lanthanum Compounds in the Series La2O3-TiO2

2010 ◽  
Vol 1265 ◽  
Author(s):  
Karl Whittle ◽  
Mark Blackford ◽  
Robert Aughterson ◽  
Katherine L Smith ◽  
Gregory R Lumpkin ◽  
...  
Keyword(s):  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Inverse Correlation ◽  
Critical Temperatures ◽  
Voltage Electron ◽  
Local Environments ◽  
Two Systems ◽  
User Facility

AbstractThin crystals of La2O3, La2/3TiO3, La2TiO5, and La2Ti2O7 have been irradiated in situ using 1 MeV Kr2+ ions in the Intermediate Voltage Electron Microscope-Tandem User Facility (IVEM-Tandem), at the Argonne National Laboratory (ANL). We observed that La2O3 remained crystalline to a fluence greater than 3.1 × 1016 ions cm-2 at a temperature of 50 K. The four binary oxide compounds in the two systems were observed through the crystalline-amorphous transition as a function of ion fluence and temperature. Results from the ion irradiations give critical temperatures for amorphisation (Tc) of 840 K for La2Ti2O7, 865 K for La2/3TiO3, and 1027 K for La2TiO5. The Tc values observed in this study, together with previous data for TiO2, are discussed with reference to the phase diagrams for La2O3-TiO2 systems and the different local environments within the crystal structures. Results suggest an observable inverse correlation between Tc and melting temperature (Tm) in the two systems.

scholarly journals Radiation-induced decomposition of U(VI) alteration phases of UO2

2006 ◽  
Vol 932 ◽  
Author(s):  
Satoshi Utsunomiya ◽  
Rodney C. Ewing
Keyword(s):  
Spent Nuclear Fuel ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Voltage Electron ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Radiation Induced ◽  
The Stability ◽  
Induced Decomposition

ABSTRACTU6+−phases are common alteration products of spent nuclear fuel under oxidizing conditions, and they may potentially incorporate actinides, such as long-lived 239Pu and 237Np, delaying their transport to the biosphere. In order to evaluate the ballistic effects of α-decay events on the stability of the U6+−phases, we report, for the first time, the results of ion beam irradiations (1.0 MeV Kr2+) for six different structures of U6+-phases: uranophane, kasolite, boltwoodite, saleeite, carnotite, and liebigite. The target uranyl-minerals were characterized by powder X-ray diffraction and identification confirmed by SAED (selected area electron diffraction) in TEM (transmission electron microscopy). The TEM observation revealed no initial contamination of uraninite in these U6+ phases. All of the samples were irradiated with in situ TEM observation using 1.0 MeV Kr2+ in the IVEM (intermediate-voltage electron microscope) at the IVEM-Tandem Facility of Argonne National Laboratory. The ion flux was 6.3 × 1011 ions/cm2/sec. The specimen temperatures during irradiation were 298 and 673 K, respectively. The Kr2+-irradiation decomposed the U6+-phases to nanocrystals of UO2 at doses as low as 0.006 dpa. The cumulative doses for the pure U6+-phases, e.g., uranophane, at 0.1 and 1 million years (m.y.) are calculated to be 0.009 and 0.09 dpa using SRIM2003. However, with the incorporation of 1 wt.% 239Pu, the calculated doses reach 0.27 and ∼1.00 dpa in ten thousand and one hundred thousand years, respectively.Under oxidizing conditions, multiple cycles of radiation-induced decomposition to UO2 followed by alteration to U6+-phases should be further investigated to determine the fate of trace elements that may have been incorporated in the U6+-phases.

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.

First X-Ray Microprobe and Microspectroscopy Results From The Gsecars Sector At The Advanced Photon Source

1997 ◽  
Vol 3 (S2) ◽  
pp. 905-906
Author(s):  
Mark L. Rivers ◽  
Stephen R. Sutton ◽  
Peter Eng ◽  
Matthew Newville
Keyword(s):  
National Laboratory ◽  
Argonne National Laboratory ◽  
Third Generation ◽  
X Rays ◽  
Environmental Sciences ◽  
X Ray ◽  
State Determination ◽  
X Ray Absorption ◽  
The Magnetic Field ◽  
Photon Source

The Advanced Photon Source (APS) at Argonne National Laboratory is a third-generation synchrotron x-ray source, optimized for producing x-rays from undulators. Such undulator sources provide extremely bright, quasi-monochromatic radiation which is ideal for an x-ray microprobe. Such microprobes can be used for trace element quantification with x-ray fluorescence, or for chemical state determination with x-ray absorption spectroscopy. The GeoSoilEnviroCARS (GSECARS) sector at the APS is building an x-ray microprobe for research in earth, planetary, soil and environmental sciences.The GSECARS undulator source is a standard APS Undulator “A” which is a 3.3 cm period device with 72 periods. The energies of the undulator peaks can be varied by adjusting the gap, and hence the magnetic field of the undulator. The energy of the first harmonic can be varied in this way from approximately 3.1 keV to 14 keV. A measured undulator spectrum is shown in Figure 1.

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.

A Membrane Deflection Fracture Experiment to Investigate Fracture Toughness of Freestanding MEMS Materials

2003 ◽  
Vol 795 ◽  
Author(s):  
H. D. Espinosa ◽  
B. Peng
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Mean Value ◽  
Advanced Materials ◽  
Ultrananocrystalline Diamond ◽  
Membrane Deflection

ABSTRACTThis paper presents a novel Membrane Deflection Fracture Experiment (MDFE) to investigate the fracture toughness of MEMS and other advanced materials in thin film form. It involves the stretching of freestanding thin-film membranes, in a fixed-fixed configuration, containing pre-existing cracks. The fracture behavior of ultrananocrystalline diamond (UNCD), a material developed at Argonne National Laboratory, is investigated to illustrate the methodology. When the fracture initiates from sharp cracks, produced by indentation, the fracture toughness was found to be 4.7 MPa m1/2. When the fracture initiates from blunt notches with radii about 100 nm, machined by focused ion beam (FIB), the mean value of the apparent fracture toughness was found to be 7.2 MPa m1/2. Comparison of these two values, using the model proposed by Drory et al. [9], provides a correction factor of 2/3, which corresponds to a mean value of ρ/2x=1/2.

Phase Transformations in Co/Nb and Co/Zr Multilayer Film Stacks.

1991 ◽  
Vol 230 ◽  
Author(s):  
J. C. Lin ◽  
R. A. Hoffman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Transformations ◽  
Multilayer Film ◽  
Isothermal Annealing ◽  
Ion Beam ◽  
Equilibrium Phase ◽  
Stable Configuration ◽  
Ion Beam Mixing ◽  
Transmission Electron

AbstractIon-beam mixing and isothermal annealing techniques were applied to induce phase transformations in Co/Nb and Co/Zr multilayer film stacks. Transmission electron microscopy(TEM) and x-ray diffraction(XRD) were used to characterize the microstructure of the films. Interfacial morphology and chemistry of the films were examined by Rutherford backscattering spectrometry(RBS) and cross-section transmission electron microscopy(XTEM). The formation of amorphous phases was found in both systems by either technique. A comparison of the phase transformation mechanisms induced by ion-beam mixing and isothermal annealing is given. The thermodynamic and kinetic factors controlling the phase formation and stability are discussed. For the isothermal annealing, the final stable configuration is predicted by equilibrium phase diagrams.

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