Reaction Diffusion Behaviour in Bronze Route Cu-Nb-Sn Superconducting Wires

2006 ◽  
Vol 258-260 ◽  
pp. 152-157
Author(s):  
Simon C. Hopkins ◽  
K.S. Tan ◽  
I. Pong ◽  
Bartek A. Glowacki
Keyword(s):  
Heat Treatment ◽  
Reaction Diffusion ◽  
Heat Treatments ◽  
Matrix Composition ◽  
Superconducting Wires ◽  
Reaction Diffusion Model ◽  
Wire Cross Section ◽  
The Wire ◽  
Diffusion Behaviour

The bronze process is a mature technology for the production of Nb3Sn superconducting wires exploiting reaction diffusion behaviour in the Cu-Nb-Sn system. However, the superconducting properties depend strongly on the applied heat treatment, and optimisation of the heat treatment is still largely by trial and improvement. Modelling of the reaction-diffusion behaviour would allow improved heat treatments to be designed; combination of this with a nondestructive in situ characterisation technique would also permit improved superconducting wires to be produced. A finite difference reaction diffusion model has been designed to permit rapid calculation of the bronze matrix composition and Nb3Sn layer thickness profiles across the wire cross-section as a function of time for any applied heat treatment. The model has also been designed to calculate the electrical resistivity of the wire, which has previously been demonstrated as a suitable in situ characterisation technique. This model has been applied to isothermal and more complex heat treatments and compared with experimental results. Good qualitative agreement has been found, and plans for further improvement of the model are described in detail.

Microstructural Development in Nb-Ti Multifilamentary Superconductors During Processing

1985 ◽  
Vol 43 ◽  
pp. 190-191
Author(s):  
A. W. West
Keyword(s):  
Heat Treatment ◽  
Critical Current Density ◽  
Copper Matrix ◽  
Wire Drawing ◽  
Heat Treatments ◽  
Microstructural Development ◽  
Final Size ◽  
Density Values ◽  
The Wire ◽  
Multifilamentary Superconductors

The influence of the filament microstructure on the critical current density values, Jc, of Nb-Ti multifilamentary superconducting composites has been well documented. However the development of these microstructures during composite processing is still under investigation.During manufacture, the multifilamentary composite is given several heat treatments interspersed in the wire-drawing schedule. Typically, these heat treatments are for 5 to 80 hours at temperatures between 523 and 573K. A short heat treatment of approximately 3 hours at 573K is usually given to the wire at final size. Originally this heat treatment was given to soften the copper matrix, but recent work has shown that it can markedly change both the Jc value and microstructure of the composite.

scholarly journals Torsion Fracture Behavior of Drawn Pearlitic Steel Wires with Different Heat Treatments

2008 ◽  
Vol 33-37 ◽  
pp. 41-46 ◽  
Author(s):  
Zhi Jia Wang ◽  
Xiao Lei Wu ◽  
You Shi Hong
Keyword(s):  
Heat Treatment ◽  
Shear Deformation ◽  
Fracture Behavior ◽  
Pearlitic Steel ◽  
Heat Treatments ◽  
Steel Wires ◽  
Short Period ◽  
The Wire ◽  
Torsion Fracture ◽  
Short Heating

In this paper, torsion fracture behavior of drawn pearlitic steel wires with different heat treatments was investigated. Samples with different heat treatment conditions were subjected to torsion and tensile tests. The shear strain along the torsion sample after fracture was measured. Fracture surface of wires was examined by Scanning Electron Microscopy. In addition, the method of Differential Scanning Calorimetry was used to characterize the thermodynamic process in the heat treatment. A numerical simulation via finite element method on temperature field evolution for the wire during heat treatment process was performed. The results show that both strain aging and recovery process occur in the material within the temperature range between room temperature and 435 °C. It was shown that the ductility measured by the number of twists drops at short heating times and recovers after further heating in the lead bath of 435 °C. On the other hand, the strength of the wire increases at short heating times and decreases after further heating. The microstructure inhomogeneity due to short period of heat treatment, coupled with the gradient characteristics of shear deformation during torsion, results in localized shear deformation of the wire. In this situation, shear cracks nucleate between lamella and the wire breaks with low number of twists.

scholarly journals Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the γ/γ′ Microstructure

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 321
Author(s):  
D. Hausmann ◽  
C. Solís ◽  
L.P. Freund ◽  
N. Volz ◽  
A. Heinemann ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Volume Fraction ◽  
Heat Treatments ◽  
Age Hardening ◽  
Precipitate Size ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Transmission Electron

Compositionally complex polycrystalline γ/γ′ CoNi-base superalloys, such as CoWAlloy2 (Co41-Ni32-Cr12-Al9-W5-Ti0.3-Ta0.2-Si0.4-Hf0.1-C-B-Zr) are interesting candidates for new high-temperature materials. To maximize their high-temperature strength, the γ/γ′ microstructure has to be optimized by adjusting the multi-step heat treatments. Various microstructures after different heat treatments were analyzed by scanning and transmission electron microscopy and especially in-situ small-angle neutron scattering during heat treatment experiments. The corresponding mechanical properties were determined by compression tests and hardness measurements. From this, an optimum γ′ precipitate size was determined that is adjusted mainly in the first precipitation heat treatment step. This is discussed on the basis of the theory of shearing of γ′ precipitates by weak and strong pair-couplings of dislocations. A second age hardening step leads to a further increase in the γ′ volume fraction above 70% and the formation of tertiary γ′ precipitates in the γ channels, resulting in an increased hardness and yield strength. A comparison between two different three-step heat treatments revealed an increase in strength of 75 MPa for the optimized heat treatment.

A Photoactivatable α5β1-Specific Integrin Ligand

2018 ◽  
Author(s):  
Roshna Vakkeel ◽  
Aleeza Farrukh ◽  
Aranzazu del Campo
Keyword(s):  
Cellular Response ◽  
Light Exposure ◽  
Matrix Composition ◽  
Cellular Behavior ◽  
Dynamic Variations ◽  
In Situ Activation ◽  
Controlled Exposure ◽  
Cellular Behaviour ◽  
Integrin Ligand

In order to study how dynamic changes of α5β1 integrin engagement affect cellular behaviour, photoactivatable derivatives of α5β1 specific ligands are presented in this article. The presence of the photoremovable protecting group (PRPG) introduced at a relevant position for integrin recognition, temporally inhibits ligand bioactivity. Light exposure at cell-compatible dose efficiently cleaves the PRPG and restores functionality. Selective cell response (attachment, spreading, migration) to the activated ligand on the surface is achieved upon controlled exposure. Spatial and temporal control of the cellular response is demonstrated, including the possibility to in situ activation. Photoactivatable integrin-selective ligands in model microenvironments will allow the study of cellular behavior in response to changes in the activation of individual integrins as consequence of dynamic variations of matrix composition.

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