The dose, temperature, and projectile-mass dependence for irradiation-induced amorphization of CuTi

1989 ◽  
Vol 4 (5) ◽  
pp. 1143-1150 ◽  
Author(s):  
J. Koike ◽  
P. R. Okamoto ◽  
L. E. Rehn ◽  
M. Meshii
Keyword(s):  
Critical Temperature ◽  
Volume Fraction ◽  
Critical Temperatures ◽  
Ion Tracks ◽  
Temperature Irradiation ◽  
Integrated Intensity ◽  
Diffraction Patterns ◽  
Amorphous Zone ◽  
The Stability ◽  
Crystalline Matrix

CuTi was irradiated with 1-MeV Ne+, Kr+, and Xe+ in the temperature range from 150 to 563 K. The volume fraction of the amorphous phase produced during room temperature irradiation with Ne+ and Kr+ ions was determined as a function of ion dose from measurements of the integrated intensity of the diffuse ring in electron diffraction patterns. The results, analyzed by Gibbons' model, indicate that direct amorphization occurs along a single ion track with Kr+, but the overlapping of three ion tracks is necessary for amorphization with Ne+. The critical temperature for amorphization increases with increasing projectile mass from electron to Ne+ to Kr+. However, the critical temperatures for Kr+ and Xe+ irradiations were found to be identical, and very close to the thermal crystallization temperature of an amorphous zone embedded in the crystalline matrix. Using the present observations, relationships between the amorphization kinetics and the displacement density along the ion track, and between the critical temperature and the stability of the irradiation-induced damage, are discussed.

The Projectile Mass Dependence of the Amorphization Process and the Critical Temperature in the Ion Irradiated CuTi

1988 ◽  
Vol 100 ◽  
Author(s):  
J. Koike ◽  
P. R. Okamoto ◽  
M. Meshii
Keyword(s):  
Critical Temperature ◽  
Crystallization Temperature ◽  
Damage Zone ◽  
Dose Dependence ◽  
Mass Dependence ◽  
Tandem Accelerator ◽  
Thermal Crystallization ◽  
Integrated Intensity ◽  
Amorphous Zone ◽  
Crystalline Matrix

ABSTRACTCuTi was irradiated with 1MeV Ne+ and Kr+ at various temperatures in the Argonne-HVEM interfaced to a tandem accelerator. The integrated intensity of diffuse ring was measured by a microdensitometer and analyzed by Gibbons model for the dose dependence of the amorphous volume. The results indicate that the direct amorphization occurs in a single damage zone with Kr+, but the overlapping of three damage zones is necessary with Ne+. The critical temperature for amorphization was 401±22K for Ne+ and 543±20K for Kr+, respectively. With Kr+, the critical temperature was nearly equal to the thermal crystallization temperature of an amorphous zone embedded in the crystalline matrix. Using the present observations, the relation between the amorphization process and the critical temperature is discussed.

scholarly journals Thermal Analysis of a MEMS-Based Self-Adaptive Microfluidic Cooling Device

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 505
Author(s):  
Gonzalo Sisó ◽  
Joana Rosell-Mirmi ◽  
Álvaro Fernández ◽  
Gerard Laguna ◽  
Montse Vilarrubi ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Stability Analysis ◽  
Critical Temperature ◽  
Thermal Resistance ◽  
Design Parameters ◽  
Linear Perturbation ◽  
Strong Nonlinearity ◽  
Critical Temperatures ◽  
The Stability ◽  
Self Adaptive

This study presents a thermal analysis of a temperature-driven microfluidic cell through a nonlinear self-adaptive micro valve that provides the mechanisms for the system to maintain a given critical temperature in an efficient way. For the description of the dynamics of the microfluidic cell, a system of two ordinary differential equations subjected to a nonlinear boundary condition, which describes the behavior of the valve, is proposed. The solution of the model, for determined conditions, shows the strong nonlinearity between the overall thermal resistance of the device and the heat flux dissipated due to the action of the thermostatic valve, obtaining a variable thermal resistance from 1.6 × 10−5 to 2.0 × 10−4 Km2/W. In addition, a stability analysis of the temperature-driven microfluidic cell is presented. The stability of the device is essential for its proper functioning and thus, to prevent its oscillating behavior. Therefore, this work focuses on assessing the range of design parameters of the self-adaptive micro valve to produce a stable behavior for the entire system. The stability analysis was performed by studying the linear perturbation around the stationary solution, with the model solved for various heat flows, flow rates, and critical temperatures. Finally, a map of the design parameters space, which specifies the region with asymptotic stability, was found. In this map, the critical temperature (temperature at which the valve initiates the buckling) plays and important role.

Moire Fringes on Precipitates in Quenched and Aged Beryllium

1968 ◽  
Vol 26 ◽  
pp. 426-427
Author(s):  
F. J. Fraikor ◽  
A. W. Brewer
Keyword(s):  
Ternary Phase ◽  
Volume Fraction ◽  
Age Hardening ◽  
Orientation Relationships ◽  
Solute Content ◽  
Moiré Fringes ◽  
Moire Patterns ◽  
Total Volume Fraction ◽  
Diffraction Patterns ◽  
Moiré Patterns

A number of investigators have examined moire patterns on precipitate particles in various age-hardening alloys. For example, Phillips has analyzed moire fringes at cobalt precipitates in copper and Von Heimendahl has reported on moire fringes in the system Al-Au. Recently, we have observed moire patterns on impurity precipitates in beryllium quenched in brine from 1000°C and aged at various temperatures in the range of 500-800°C. This heat treatment of beryllium rolled from vacuum cast ingots produces the precipitation of both an fee ternary phase, AlFeBe4, and an hcp binary phase, FeBe11. However, unlike a typical age-hardening alloy, the solute content of this material is low (less than 1000 ppm of Fe and 600 ppm of Al) and hence the total volume fraction of precipitates is small. Therefore there is some difficulty in distinguishing the precipitates and their orientation relationships with the beryllium matrix since the weak precipitate spots generally do not appear on the diffraction patterns.

Direct imaging of order-disorder and antiphase domain structures in Ti3Al intermetallic compound

1990 ◽  
Vol 48 (4) ◽  
pp. 480-481
Author(s):  
H. Q. Ye ◽  
T.S. Xie ◽  
D. Li
Keyword(s):  
Intermetallic Compound ◽  
Volume Fraction ◽  
Fundamental Problem ◽  
Antiphase Domain ◽  
Atomic Scale ◽  
Orientation Relationships ◽  
Domain Structures ◽  
Α Phase ◽  
Diffraction Patterns ◽  
Two Phases

The Ti3Al intermetallic compound has long been recognized as potentially useful structural materials. It offers attractive strength to weight and elastic modulus to weight ratios. Recent work has established that the addition of Nb to Ti3Al ductilized this compound. In this work the fundamental problem of this alloy, i.e. order-disorder and antiphase domain structures was investigated at the atomic scale.The Ti3Al+10at%Nb alloys used in this study were treated at 1060°C and then aged at 700°C for 2 hours. The specimens suitable for TEM were prepared by standard jet electrolytic-polishing technique. A JEM-200CX electron microscope with an interpretable resolution of about 0.25 nm was used for HREM.The [100] and [001] projections of the α2 phase were shown in Fig.l.The alloy obtained consist of at least two phases-α2(Ti3Al) and β0 structures. Moreover, a disorder α phase with small volume fraction was also observed. Fig.2 gives [100] and [001] diffraction patterns of the α2 phase. Since lattice parameters of the ordered α2 (a=0.579, c=0.466 nm) and disorder α phase (a0=0.294≈a/2, c0=0.468 nm) are almost the same, their diffraction patterns are difficult to be distinguished when they are overlapped with epitaxial orientation relationships.

scholarly journals TEMPERATURE CHARACTERISTICS FOR PULSATION FREQUENCY IN GONIONEMUS

1928 ◽  
Vol 11 (5) ◽  
pp. 547-562 ◽  
Author(s):  
Ernst Wolf
Keyword(s):  
Critical Temperature ◽  
Functional Unit ◽  
Temperature Characteristic ◽  
Nerve Ring ◽  
Pulsation Frequency ◽  
Sense Organs ◽  
Critical Temperatures ◽  
Temperature Characteristics ◽  
System A ◽  
Definite Temperature

The frequency of contraction of the bell of Gonionemus was studied in relation to temperature, with intact animals and also where different operations were made on the nervous system. A number of values of µ are found for intact animals namely 8,100±, 10,500±, 32,000± and 22,500±, with critical temperatures at 9.6°, 12.3°, and 14.0°. Four different classes of operations were used: (1) Animals where the nerve ring was cut on two opposite sides of the bell; the µ values found are 10,500± and 21,300±, with a critical temperature at 13.4°. (2) Animals with four cuts through the nerve ring gave µ = 10,600 ± and µ = 21,000, with a critical temperature at 13.1°. (3) In animals where the bell was cut in half the temperature characteristic was found to be 16,900. And finally (4) in the animals where the nerve ring was totally removed µ values of 8,100, 16,000±, and 29,000 were found, with critical temperatures at 15.0° and 9.4°. These results are discussed from the standpoint of the theory which supposes that definite "temperature characteristics" may be associated with the functional activity of particular elements in a complex functional unit, and that these elements may be separately studied and identified by suitable experimental procedures involving the magnitudes of the respective temperature characteristics and the locations of associated critical temperatures. The swimming bell of medusæ with its marginal sense organs permits a fairly direct approach to such questions. It is found that even slight injuries to the marginal nerve ring, for example, produce specific modifications in the temperature relations which are different from those appearing when the organism is cut in half.

Crystalline-To-Amorphous Transformation of Intermetallic Compounds in the Zr-Fe-M System Induced by Irradiation

1994 ◽  
Vol 373 ◽  
Author(s):  
Arthur T. Motta ◽  
Lawrence M. Howe ◽  
Paul R. Okamoto
Keyword(s):  
Critical Temperature ◽  
Low Temperature ◽  
Dose Rate ◽  
Intermetallic Compounds ◽  
Electron Energy ◽  
Energy Dependence ◽  
Electron Irradiation ◽  
Critical Temperatures ◽  
Lower Critical Temperature ◽  
Ternary Intermetallic Compounds

AbstractThe binary and ternary intermetallic compounds Zr3Fe, Zr2 Fe, (Zr0.5,Nb0.5)3Fe, Zr3(Fe0.9,Ni0.1) and Zr3(Fe0.5,Ni0.5) were subjected to 900 keV electron irradiation until amorphous to study the change in the dose-to-amorphization with temperature. The critical temperatures were observed to vary with dose rate, and with the type of compound. Hexagonal (Zr0.5,Nb0.5)3Fe had an appreciably lower critical temperature and higher dose to amorphization at low temperature than orthorombic Zr3Fe, whereas other orthorombic Zr3(Fex,NiI-x) compounds were essentially identical in behavior to Zr3Fe. The electron energy dependence of the dose-to-amorphization was studied in Zr3Fe between 250 and 900 keV. The analysis of the results gives displacement energies of EZrd = 26 eV, EFed = 18 eV in the Zr3Fe compound.

scholarly journals Strong correlation between electronic bonding network and critical temperature in hydrogen-based superconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Belli ◽  
Trinidad Novoa ◽  
J. Contreras-García ◽  
Ion Errea
Keyword(s):  
Critical Temperature ◽  
Physical Properties ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Strong Correlation ◽  
Critical Temperatures ◽  
Structural And Electronic Properties ◽  
Superconducting Compounds ◽  
Better Than

AbstractBy analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.

scholarly journals Investigation of the features of phase formation in the joint aluminothermic reduction of ZrO2, Ta2O5, Nb2O5

2019 ◽  
Vol 60 (11) ◽  
pp. 79-84
Author(s):  
Andrey S. Russkih ◽  
◽  
Sergey N. Agafonov ◽  
Artem A. Ponomarenko ◽  
◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Formation ◽  
Volume Fraction ◽  
Rare Metal ◽  
Scientific Basis ◽  
Aluminothermic Reduction ◽  
Powder Size ◽  
Analysis Instrument ◽  
Diffraction Patterns ◽  
American Society

In this paper, we consider the advantage of using the metallothermic method for producing alloys, in contrast to traditional methods. Using the HSC Chemistry 6.1 software package, thermodynamic modeling was performed. The possibility of obtaining intermetallic compounds by the joint aluminothermic reduction of Zr, Ta, Nb oxides is shown. The alloy was obtained by aluminothermic reduction of aluminum, zirconium, tantalum and niobium oxides in a resistance furnace, followed by grinding and powder size 40-100 microns. An experimental study of the sequence of phase formation and the boundaries of their existence was investigated using differential thermal analysis (DTA). The experiment was carried out on a STA 449 F3 Jupiter (NETZSCH) synchronous thermal analysis instrument in an argon flow GOST 10157-79 (the volume fraction of argon is at least 99.993%), the flow rate of the gas used was 30 ml/min. X-ray phase analysis (XRD) of the products (after DTA) was carried out on an XRD 7000 diffractometer (Shimadzu). By the relative intensity of the lines of the various phases, their quantitative ratio was estimated. The diffraction patterns were decoded using literature data, as well as the JCPDS (International Center For Diffraction Data) and ASTM (American Society for Testing and Materials) databases. According to the obtained XRD data, in the sample at temperatures of 954.5 and 1309.1 ºС, respectively, the formation of a solid solution (Zr, Nb, Ta)Al2 occurs, which is isostructural to the intermetallic Al3Zr. In both cases, the concomitant ZrAl2 intermetallic compound is also formed. The performed study can serve as a scientific basis for the development of promising metallothermal technologies for the production of rare metal alloys.

scholarly journals On the Stability of 3C-SiC Single Crystals at High Temperatures

2012 ◽  
Vol 717-720 ◽  
pp. 493-496
Author(s):  
Deborah Dompoint ◽  
Irina G. Galben-Sandulache ◽  
Alexandre Boulle ◽  
Didier Chaussende ◽  
Dominique Eyidi ◽  
...  
Keyword(s):  
Single Crystals ◽  
Volume Fraction ◽  
Diffuse Intensity ◽  
X Ray ◽  
Partial Dislocations ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
The Stability ◽  
Kinetics Of ◽  
Evolution With Time

The 3C-6H polytypic transition in 3C-SiC single crystals is studied by means of diffuse X-ray scattering (DXS) coupled with transmission electron microscopy (TEM). TEM reveals that the partially transformed SiC crystals contain regions of significantly transformed SiC (characterized by a high density of stacking faults) co-existing with regions of pure 3C-SiC. The simulation of the diffuse intensity allows to determine both the volume fraction of transformed material and the transformation level within these regions. It is further shown that the evolution with time and temperature of the transition implies the multiplication and glide of partial dislocations, the kinetics of which are quantified by means of DXS.

A Variable Viscosity Approach for the Analysis of Steady State and Dynamic Characteristics of Two-Lobe Journal Bearing With TiO2 Based Nanolubricant

2017 ◽  
Author(s):  
Ashutosh Kumar ◽  
Sashindra Kumar Kakoty
Keyword(s):  
Steady State ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Volume Fraction ◽  
Variable Viscosity ◽  
Flow Coefficient ◽  
Viscosity Model ◽  
Nano Lubricant ◽  
The Stability ◽  
Stiffness And Damping

Steady-state and dynamic characteristics of two-lobe journal bearing, operating on TiO2 based Nano-lubricant has been obtained. The effective viscosity is obtained by using Krieger-Dougherty viscosity model for a given volume fraction of nanoparticle in the base fluid. Various bearing performance characteristics are then obtained by solving modified Reynolds equation for variable viscosity model and couple stress model. The stiffness and damping coefficients are also determined for various values of the volume fraction of the nanoparticle in the nanofluid. Results reveal that load carrying capacity and flow coefficient increase whereas friction variable decreases without affecting the stability condition of two-lobe journal bearing operating on TiO2 based nanolubricant. On the other hand attitude angle and dynamic coefficients remains constant for all the values of volume fraction of nanoparticle.

Sign in / Sign up

Export Citation Format

Share Document