Amorphisation Tendency of Intermetallic Compounds Under Electron Irradiation

1986 ◽  
Vol 74 ◽  
Author(s):  
D. E. Luzzi ◽  
M. Meshii
Keyword(s):  
Crystal Structure ◽  
Intermetallic Compounds ◽  
Electron Irradiation ◽  
Alloy System ◽  
Metal Compounds ◽  
Complex Crystal Structure ◽  
In Situ Experiments ◽  
Binary Alloy System ◽  
Disordered Crystal

AbstractThe chemical disordering model for the electron irradiation induced crystalline to amorphous (C-A) transition was previously developed using in-situ experiments in the intermetallic compounds of the Cu-Ti binary alloy system. In the context of this model, a rule was developed which predicts the amorphisation tendency of these and other binary intertransition metal compounds with an accuracy of 92% in the 38 compounds studied to date. Two aspects of this rule, the composition of the compound and the crystal structure are examined through a first approximation computer comparison of ordered, partially ordered, and disordered crystal structures. It is found that in bcc based compounds and in complex crystal structure compounds, the ability of the chemical disordering to raise the energy of the crystal is severely inhibited at compound compositions away from 50:50. During the disordering process, the greatest increase of the crystal energy occurs during the early stages of chemical disordering. These results mesh well with the concept of an amorphous transition driven by the energy increase due to chemical disordering.

Application of Hrem in Studying Amorphisation of Intermetallic Compounds

1985 ◽  
Vol 62 ◽  
Author(s):  
D. E. Luzzi ◽  
H. Mori ◽  
H. Fujita ◽  
M. Meshii
Keyword(s):  
High Resolution ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Electron Irradiation ◽  
Driving Force ◽  
Amorphous Materials ◽  
Alloy System ◽  
Amorphous Structure ◽  
Ti Alloy ◽  
Special Significance

ABSTRACTElectron irradiation induces many intermetallic compounds to become amorphous. As this irradiation is capable of producing only isolatedpoint defects for each collision event, an understanding of this amorphisation proqess has a special significance with respect to the understanding of amorphous materials. This paper will report the results of HREM observations of an intermetallic compound in the Cu-Ti alloy system. High resolution micrographs will be presented to demonstrate that the energy associated with the irradiation induced chemical disordering is the major driving force in the amorphisation process. Also, the utility of the HREM in the study of amorphisation and the amorphous structure will be discussed.

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.

Non-equilibrium phase formation

1990 ◽  
Vol 48 (4) ◽  
pp. 506-507
Author(s):  
Hiroshi Fujita
Keyword(s):  
Electron Irradiation ◽  
Equilibrium Phase ◽  
General Rule ◽  
High Energy ◽  
Atomic Scale ◽  
Irradiation Effect ◽  
In Situ Experiments ◽  
Equilibrium Phases ◽  
Non Equilibrium

The most important advantage of EM’s is in situ experiments on detailed processes of the same phenomena that occur in bulk materials. In recent years, in situ experiments with HVEM’s, in particular with a 3MV ultra-HVEM , has made it possible to create non-equilibrium phases, which do not exist in nature, or to control and design materials on an atomic scale. Namely, HVEM’s have developed to “Micro-Laboratory”, in which various material-treatments can be done, for natural science from powerful tools for characterization and/or identification of materials.l.The General Rule for Solid Amorphization The author and his cowerkers have succeeded in making amorphous solids of intermetallic compounds by high energy electron irradiation. Using the electron irradiation effect, necessary conditions for the formation of both non-equilibrium phases and extremly supersaturated solid structures[3,4] can be easily and precisely controlled.

Directional disordering prior to amortization in electron-irradiated Cu-Ti intermetallic compounds

1989 ◽  
Vol 47 ◽  
pp. 656-657
Author(s):  
D.E. Luzzi
Keyword(s):  
Intermetallic Compounds ◽  
Experimental Studies ◽  
Structural Evolution ◽  
Superlattice Reflection ◽  
Alloy System ◽  
High Energy ◽  
Ex Situ ◽  
Electron Dose ◽  
Ewald Sphere ◽  
Binary Alloy System

At temperatures below approximately 265 K, intermetallic compounds in the Cu-Ti binary alloy system undergo an amorphizat ion transformation when irradiated by high energy electrons. Previous in-situ experimental studies revealed that the irradiation first induces chemical disordering in the compound (seen as a reduction in superlattice reflection intensity) which is followed by the crystalline-amorphous (C-A) transition. However, the actual structural evolution of the material during the C-A transition was not addressed in the previous study.In the present study, the structural evolution of the compound Cu4Ti3 was studied by ex-situ diffraction experiments in irradiated material that had not received a sufficient electron dose for amorphization. Cu4Ti3 has a Frank-Kasper-type tetragonal crystal structure composed of seven stacked body-centeredtetragonal sublattices.In Fig. 1, a diffraction pattern of the (017) systematic reflections is shown prior to complete amorphization. The double arrows mark the location of intersections of the first-order amorphous halo with the second-order halo arising from the (017) reflections and the Ewald sphere.

In-situ observation of the crystal structure transition of Pt-Sn intermetallic nanoparticles during deactivation and regeneration

2021 ◽  
Author(s):  
Ze-Qi Zhang ◽  
Yuchen Pei ◽  
Mingjun Xiao ◽  
Guowen Hu ◽  
Zhi-Peng Huang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Catalytic Activity ◽  
Intermetallic Compounds ◽  
In Situ Observation ◽  
Structure Transition ◽  
Atomic Structures ◽  
Intermetallic Nanoparticles

Intermetallic compounds nanoparticles (iNPs) have attracted great attention as efficient catalysts for improved activity and selectivity. As the catalytic activity of the iNPs is strongly associated with their atomic structures,...

Evidence of a novel intermetallic Mg7Ag3 phase in Mg–Ag binary alloy system

2018 ◽  
Vol 51 (3) ◽  
pp. 844-848 ◽  
Author(s):  
Yuping Ren ◽  
Hong Zhao ◽  
Liqing Wang ◽  
Bo Yang ◽  
Hongxiao Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Binary Alloy ◽  
Electron Backscatter Diffraction ◽  
Alloy System ◽  
Rietveld Analysis ◽  
Crystallographic Structure ◽  
Orthorhombic Symmetry ◽  
Diffraction Patterns ◽  
Binary Alloy System

A novel intermetallic Mg7Ag3 phase in the Mg–Ag binary alloy system at 573 and 623 K was discovered by the diffusion couple technique combined with the equilibrated alloy method. The composition and crystal structure of the Mg7Ag3 phase were identified via scanning electron microscopy/energy dispersive spectrometry, X-ray diffractometry (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The refinement of the XRD patterns was performed by Rietveld analysis. The XRD data have shown that Mg7Ag3 crystallizes in a body-centered crystal structure with Immm/orthorhombic symmetry (space group No. 71) and lattice parameters a = 14.2172, b = 14.6184, c = 14.177 Å and α = 90°. The well indexed selected area electron diffraction patterns and Kikuchi pattern obtained from TEM and EBSD confirmed the crystallographic structure obtained by XRD.

The role of second phase particles and grain boundaries on recrystallization: Quasi-in situ experiments and modeling in U-10Mo alloy system

2021 ◽  
pp. 153445
Author(s):  
Jacqueline I. Reeve ◽  
Benjamin J. Schuessler ◽  
William E. Frazier ◽  
David P. Field ◽  
Vineet V. Joshi
Keyword(s):  
Grain Boundaries ◽  
Alloy System ◽  
Second Phase ◽  
Second Phase Particles ◽  
In Situ Experiments

Real disordered crystal structure and Curie temperature of intermetallic compounds Y2Fe17−xMx (M=Si or Al)

2001 ◽  
Vol 315 (1-2) ◽  
pp. 82-89 ◽  
Author(s):  
V.I. Voronin ◽  
I.F. Berger ◽  
A.G. Kuchin ◽  
D.V. Sheptyakov ◽  
A.M. Balagurov
Keyword(s):  
Crystal Structure ◽  
Curie Temperature ◽  
Intermetallic Compounds ◽  
Disordered Crystal

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

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.

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