SUPERCONDUCTING PROPERTIES OF (Tl0.64Bi0.16Pb0.2)Ba2−xSrxCa3Cu4Oy BY LIQUID-GAS-SOLIDIFICATION PROCESSING

1991 ◽  
Vol 05 (26) ◽  
pp. 1735-1743
Author(s):  
H. CHOU ◽  
H.S. CHEN ◽  
E.M. GYORGY ◽  
A.R. KORTAN ◽  
L.C. KIMERLING ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Solidification Process ◽  
Tetragonal Structure ◽  
Layer Formation ◽  
Superconducting Properties ◽  
Solidification Processing ◽  
Resistivity Measurements ◽  
Percolation Limit ◽  
Non Equilibrium

The effect of Sr substitution in (Tl0.64Bi0.16Pb0.2)Ba2−xSrxCa3Cu4Oy(x=0, 1, 2) superconductors is studied by liquid-gas-solidification process. (Tl0.64Bi0.16Pb0.2)Ba2−x SrxCa3Cu4Oy forms a tetragonal structure, with a c axis decreasing with Sr content. The substitution of Sr tends to suppress Cu-O layer formation. It also slows down the phase transformation from Tl-rich to Tl-poor phases which may be attributed to a phase equilibration of kinetic origin. The superconducting crystals grow under non-equilibrium and anisotropic conditions, and exhibit platelet and dentritic morphologies. The resistivity measurements indicate percolation effects with a percolation limit of just above 8% of the high Tc phase.

Highly Textured Superconducting Bi2Sr2CaCu2Oy Crystals Prepared by Unidirectional Solidification Processing

1989 ◽  
Vol 169 ◽  
Author(s):  
Y. Shiohara ◽  
T. Oyama ◽  
M. Nakagawa ◽  
T. Suga ◽  
K. Ishige ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Local Equilibrium ◽  
Equilibrium Phase ◽  
Processing Parameters ◽  
Zone Melting ◽  
Unidirectional Solidification ◽  
Floating Zone ◽  
Solidification Processing ◽  
Vertical Bridgman ◽  
Superconducting Oxides

AbstractUnidirectional solidification processing, including Floating Zone Melting, Vertical Bridgman, and Laser Zone Melting methods for making high Tc superconducting oxides has been investigated. The effects of processing parameters, growth rate (R) and temperature gradient (G), on texture, morphology, and structures of unidirectionally grown crystals were investigated. Two different crystallization mechanisms were recognized, one is non‐equilibrium phase transformation under high GR conditions, and the other is due to local equilibrium phase transformation under low GR conditions. Strongly aligned structures were obtained at high G/R ratios with low GR value. The interrelation between the superconducting characteristics and textured structure produced were also discussed.

White layer formation due to phase transformation in orthogonal machining of AISI 1045 annealed steel

2008 ◽  
Vol 488 (1-2) ◽  
pp. 195-204 ◽  
Author(s):  
Sangil Han ◽  
Shreyes N. Melkote ◽  
Michael S. Haluska ◽  
Thomas R. Watkins
Keyword(s):  
Phase Transformation ◽  
White Layer ◽  
Layer Formation ◽  
Orthogonal Machining ◽  
Aisi 1045 ◽  
Annealed Steel ◽  
White Layer Formation

Solidification of Al-Pb Alloy under the Effect of Micro-Alloying Element Ti and C

2016 ◽  
Vol 879 ◽  
pp. 2439-2443 ◽  
Author(s):  
Qian Sun ◽  
Hong Xiang Jiang ◽  
Jiu Zhou Zhao
Keyword(s):  
Phase Transformation ◽  
Liquid Phase ◽  
Microstructure Evolution ◽  
Solidification Process ◽  
Miscibility Gap ◽  
Kinetic Behavior ◽  
Number Density ◽  
Alloying Element ◽  
Refinement Efficiency ◽  
Line Temperature

Experiments were carried to investigate the effect of TiC on the solidification process and microstructure of Al-Pb alloys. It is demonstrated that TiC particles are effective inoculants for the nucleation of the Pb-rich droplets during cooling an Al-Pb alloy in the miscibility gap. A model describing the kinetic behavior of TiC particles in the melt and the liquid-liquid decomposition of Al-Pb was developed. The dissolution, coarsening and precipitation processes of TiC particles as well as the microstructure evolution during the liquid-liquid phase transformation of an Al-Pb alloy were calculated. The numerical results indicate that what determines the refinement efficiency of TiC particles on the Pb-rich droplets/particles is the number density of TiC particles in the melt cooled to the binodal line temperature of the Al-Pb alloy. If the number density of TiC particles in the melt before the beginning of the liquid-liquid decomposition is high enough, the addition of TiC causes a refinement of the Pb-rich droplets/particles and promotes the formation of Al-Pb alloys with a well dispersed microstructure.

scholarly journals On the Impact of Microsegregation Model on the Thermophysical and Solidification Behaviors of a Large Size Steel Ingot

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 74
Author(s):  
Chunping Zhang ◽  
Mohammad Jahazi ◽  
Paloma Isabel Gallego
Keyword(s):  
Thermophysical Properties ◽  
Steel Ingot ◽  
Solidification Process ◽  
Lever Rule ◽  
Cast Ingot ◽  
Classical Equilibrium ◽  
Large Size ◽  
Macro Scale ◽  
The Impact ◽  
Non Equilibrium

The impact of microsegregation models on thermophysical properties and solidification behaviors of a high strength steel was investigated. The examined microsegregation models include the classical equilibrium Lever rule, the extreme non-equilibrium Scheil-Gulliver, as well as other treatments in the intermediate regime proposed by Brody and Flemings, Clyne and Kurz, Kobayashi and Ohnaka. Based on the comparative analyses performed on three representative regions with varied secondary dendrite arm spacing sizes, the classical equilibrium Lever rule and non-equilibrium Scheil scheme were employed to determine the thermophysical features of the studied steel, using the experimentally verified models from literature. The evaluated thermophysical properties include effective thermal conductivity, specific heat capacity and density. The calculated thermophysical data were used for three-dimensional simulation of the casting and solidification process of a 40 metric ton steel ingot, using FEM code Thercast®. The simulations captured the full filling, the thermo-mechanical phenomena and macro-scale solute transport in the cast ingot. The results demonstrated that Lever rule turned out to be the most reasonable depiction of the physical behavior of steel in study in large-size cast ingot and appropriate for the relevant macrosegregation simulation study. The determination of the model was validated using the experimentally measured top cavity dimension, the thermal profiles on the mold outside surface by means of thermocouples, and the carbon distribution patterns via mass spectrometer analysis.

Ion-Irradiation Effects in Tl2Ca2Ba2Cu3010 Superconductors

1989 ◽  
Vol 169 ◽  
Author(s):  
J. C. Barbour ◽  
J. F. Kwak ◽  
E. L. Venturini ◽  
D. S. Ginley ◽  
P. S. Peercy
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Ion Irradiation ◽  
Superconducting Properties ◽  
Irradiation Effects ◽  
Atomic Collisions ◽  
Dominant Mechanism ◽  
Resistivity Measurements ◽  
Helium Ion ◽  
Deposited Energy

AbstractThe effects of oxygen and helium ion irradiation on the superconducting properties of Tl2Ca2Ba2Cu3010 thin films were investigated. The transition temperature and width were monitored as a function of ion fluence using both magnetization and resistivity measurements. These data suggest that superconductivity is completely suppressed at 0.020 dpa for both He and 0 ion irradiation. Further, the rate of decrease in Tc as a function of deposited energy showed that the dominant mechanism causing damage-induced suppression of Tc in these films was from atomic collisions.

Synthesis and Characterization of Low Density Bi-2223 Cuprates Superconductor Doped Eu2O3 Nanoparticles

2021 ◽  
Vol 317 ◽  
pp. 131-137
Author(s):  
Suhaimi Nurbaisyatul Ermiza ◽  
Azhan Hashim ◽  
Azman Kasim ◽  
Norazila Ibrahim ◽  
Siti Fatimah Saipuddin
Keyword(s):  
Solid State Reaction Method ◽  
Synthesis And Characterization ◽  
Crystallographic Structure ◽  
Low Density ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Resistivity Measurements

Bi1.6Pb0.4Sr2Ca2-xEuxCu3Oδ cuprates superconductor doped with Eu nanoparticles (x = 0.0000, 0.0025, 0.0200 and 0.0500) were synthesized through conventional solid state reaction method. Crystalline sucrose was added during pelletization and burn at 400°C for two hours to create low density sample. The effect of doping Eu2O3 nanoparticles on the structural and superconducting properties by means of critical temperature (Tc), critical current density (Jc), X-ray diffraction (XRD) together with Field Emission Scanning Electron Microscopy (FESEM) and Alternating Current Susceptibility (ACS) were studied. Based on XRD analyses, the crystallographic structure has shown slightly changed from tetragonal to orthorhombic. The amount of 2223 phase gradually decreased with the increment of Eu concentration which indicates that Eu nanoparticles substitution favours the growth of 2212 phases. The resistivity measurements show that the highest Tcvalue for doped samples found at 90 K for x = 0.0025. The FESEM images showed that the plate-like grains become smaller and distributed randomly without specific alignment due to the increment of Eu concentration.

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