Morphology and Structure of Nb3Sn Diffusion Layers in Superconductors with Tubular Nb Filaments

2015 ◽  
Vol 364 ◽  
pp. 139-146
Author(s):  
Elena N. Popova ◽  
I.L. Deryagina ◽  
E.I. Patrakov ◽  
E.G. Valova-Zaharevskaya
Keyword(s):  
Electron Microscopy ◽  
Diffusion Annealing ◽  
Structure And Morphology ◽  
Diffusion Layers ◽  
Morphology And Structure ◽  
Columnar Grains ◽  
Equiaxed Grains ◽  
Complete Transformation ◽  
Bronze Matrix

The structure and morphology of Nb3Sn layers in superconducting Nb/Cu-Sn composites with ring (tubular) Nb filaments have been studied by transmission (TEM) and scanning (SEM) electron microscopy after various regimes of diffusion annealing. It is demonstrated that the tubular geometry of Nb filaments, in which Sn diffuses from the bronze matrix both from inside and outside, ensures practically complete transformation of Nb into the superconducting Nb3Sn phase. Besides, at certain regimes of the diffusion annealing this geometry enables the improvement of the superconducting layers morphology compared to that of wires with continuous filaments, namely, to obtain wide Nb3Sn layers with fine equiaxed grains and to avoid the formation of columnar grains, which promotes enhanced current-carrying capacities of the wires.

Effect of Annealing on Nanocrystalline Structure of Nb3Sn Diffusion Layers in Composites with Internal Tin Sources

2010 ◽  
Vol 297-301 ◽  
pp. 126-131 ◽  
Author(s):  
E.N. Popova ◽  
Vladimir V. Popov ◽  
E.P. Romanov ◽  
S.V. Sudareva ◽  
L.V. Elohina ◽  
...  
Keyword(s):  
Grain Size ◽  
Carrying Capacity ◽  
Nanocrystalline Structure ◽  
Diffusion Annealing ◽  
External Diameter ◽  
High Temperature Annealing ◽  
Grain Sizes ◽  
Diffusion Layers ◽  
Average Grain Size ◽  
Complete Transformation

Multifilamentary Nb3Sn-based superconducting composites manufactured by an internal-tin method have been studied by transmission (TEM) and scanning (SEM) electron microscopy. The main goal of this study is to reveal the effect of diffusion annealing regimes as well as the external diameter of the wires on the structure of nanocrystalline Nb3Sn layers (average grain size, grain size distribution, layer thickness, amount of Sn, etc.). It is demonstrated that multistep diffusion annealing results in quite a complete transformation of Nb filaments into Nb3Sn though some amount of the residual Nb remains in the filaments center. With an external diameter decrease the superconducting layers structure has been found to refine and get somewhat more uniform. An additional high-temperature annealing results in marked growth of Nb3Sn grain sizes and their scattering in sizes, which may negatively affect the current-carrying capacity of a wire.

Solid-State Diffusion Formation of Nanocrystalline Nb3Sn Layers at Two-Staged Annealing of Multifilamentary Nb/Cu-Sn Wires

2012 ◽  
Vol 16 ◽  
pp. 69-75 ◽  
Author(s):  
E.N. Popova ◽  
I.L. Deryagina ◽  
E.P. Romanov ◽  
E.A. Dergunova ◽  
A.E. Vorobyova ◽  
...  
Keyword(s):  
Diffusion Annealing ◽  
Solid State Diffusion ◽  
Superconducting Layer ◽  
Superconducting Wires ◽  
Second Stage ◽  
State Diffusion ◽  
Columnar Grains ◽  
Average Size ◽  
Bronze Matrix ◽  
Active Formation

The structure of Nb3Sn-based, bronze-processed Ti-doped multifilamentary superconducting wires has been studied by TEM and SEM after the first (5750C,100 h) and the second (6500C,100 h) stage of the diffusion annealing. The Nb3Sn layers formation in all the composites proceeds by one and the same mechanism and starts with nucleation of particles and very fine grains of this phase in Nb filaments where Sn diffuses from the bronze matrix. Ti, inserted both in the bronze matrix, or Nb filaments, diffuses into the growing superconducting layer and promotes its more active formation. At the first stage of annealing (5750C, 100 h) Nb3Sn grains have an average size of 40 nm, and at the second stage (6500C, 100 h) they increase by a factor of 1.5 and the grain size distribution gets wider. After the two-stage annealing the amount of the residual niobium is small, and some Nb filaments, especially in doped composites, almost completely transform into Nb3Sn. In the Nb3Sn layers of a zone of columnar grains is adjacent to the residual Nb.

Electron Microscopy of InN Films

1989 ◽  
Vol 162 ◽  
Author(s):  
J. S. Morgan ◽  
T. J. Kistenmacher ◽  
W. A. Bryden ◽  
T. O. Poehler
Keyword(s):  
Electron Microscopy ◽  
Defect Structure ◽  
Growth Morphology ◽  
Plan View ◽  
Mechanical Abrasion ◽  
Transmission Electron ◽  
Morphology And Structure ◽  
Columnar Grains ◽  
Amorphous Quartz ◽  
Scanning Electron

ABSTRACTThis paper describes growth morphology and structure of rfmagnetron sputtered thin films of InN, studied by plan-view transmission electron microscopy (TEM) and by scanning electron microscopy (SEM). Films deposited on TEM grids, (0001) sapphire, (111) silicon and amorphous quartz were prepared for TEM by mechanical abrasion of the substrate followed by sputter etching. At low deposition temperatures (<400°C), films consisted of small, basal-oriented, columnar grains. Above 500°C, growth consisted of larger, faceted, basal-oriented, mesa-island grains. Observations of growth morphology and defect structure are correlated with structural, compositional and electrical properties.

Effect of Multifilamentary Nb/Cu-Sn Wire Diameter on the Nb3Sn Diffusion Layers Structure

2011 ◽  
Vol 312-315 ◽  
pp. 289-294 ◽  
Author(s):  
E.N. Popova ◽  
E.P. Romanov ◽  
I.L. Deryagina ◽  
S.V. Sudareva ◽  
E.A. Dergunova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Nanocrystalline Structure ◽  
Reactive Diffusion ◽  
External Diameter ◽  
Mean Square ◽  
Mean Square Deviation ◽  
Diffusion Layers ◽  
Nanocrystalline Layer ◽  
Average Size ◽  
Bronze Matrix

Bronze-processed Nb3Sn-based multifilamentary composites with external diameter of 0.8 and 0.5 mm and coupled Nb filaments have been studied by transmission (TEM) and scanning (SEM) electron microscopy. After the two-staged annealing, 575°С, 150 h + 650°С, 200 h, commonly used for ITER conductors, a nanocrystalline layer of superconducting Nb3Sn compound is formed in every Nb filament as a result of solid-state reactive diffusion of Sn from the bronze matrix. It is demonstrated that in the wires of smaller external diameter the Nb filaments transformation into the Nb3Sn compound is more pronounced, that is the amount of the residual Nb is smaller. Besides, the nanocrystalline structure of the Nb3Sn diffusion layers is more perfect in 0.5 mm diameter wires, namely, the Nb3Sn grains are finer (their average size being 60 nm compared to 70 nm in 0.8 mm diameter wires) and are more uniform in sizes (the root mean square deviation of grain size distribution is correspondingly 15 and 17 nm).

Morphology and Structure of Diffusion Layers in Nb3Sn-Based Superconductors of Different Geometry

2015 ◽  
Vol 5 ◽  
pp. 199-225 ◽  
Author(s):  
Elena N. Popova ◽  
I.L. Deryagina
Keyword(s):  
Superconducting Phase ◽  
Inorganic Materials ◽  
Diffusion Reaction ◽  
Diffusion Annealing ◽  
Structure And Morphology ◽  
Diffusion Layers ◽  
State Diffusion ◽  
Structure Morphology ◽  
Evolution Of Structure ◽  
Ti Doping

The evolution of structure and morphology of superconducting Nb3Sn layers forming under various regimes of the diffusion annealing in multifilamentary Nb/Cu–Sn superconductors of different design is briefly reviewed based on the authors’ (with their coauthors) original studies and the available publications. Different modes of the solid-state diffusion formation of the superconducting phase are compared. Possible mechanisms of the Nb3Sn nucleation upon the diffusion reaction of the Nb filaments and bronze matrixes are discussed. The effects of different doping elements, especially Ti, on the formation of the superconducting phase, its structure and morphology, and, consequently, on the current-carrying capacities of multifilamentary Nb3Sn-based wires are considered. Special attention is paid to the effect of the mode of Ti doping, the content of this alloying element and the regimes of the diffusion annealing on the structure, morphology and resulting performance of the bronze-processed wires with coupled Nb filaments worked out at Bochvar Institute of Inorganic Materials for the creation of International Thermonuclear Experimental Reactor.

Characteristic of a Novel Composite Inorganic Polymer Coagulant-PAZF Prepared from Industrial Wastes

2014 ◽  
Vol 977 ◽  
pp. 82-85
Author(s):  
Ming Li ◽  
Yan Zhen Yu ◽  
Juan Ting Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Complex Compounds ◽  
Industrial Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Morphology ◽  
Coagulation Performance ◽  
Composite Coagulant ◽  
Scanning Electron

A new composite coagulant polymeric aluminum zinc ferric (PAZF) was synthesized from industrial wastes. The structure and morphology of the coagulant was characterized by X-ray Diffraction (XRD), Infrared Spectroscopy (IR) and Scanning Electron Microscopy (SEM) and the coagulation performances were evaluated by dyeing-printing wastewater treatment. The results show that new complex compounds are formed in PAZF. Compared with poly aluminum chloride (PAC), the contents of ionic polymerized bonds and the cross-copolymerization among Fe (III), Al (III) and Zn (II) hydroxyl polymerized bonds are increase obviously, and the surface morphology of PAZF presents a net-like structure with the longer molecular chain. Coagulation experiments indicate that PAZF exhibits better coagulation performance in removing turbidity, COD and chromaticity.

Formation of Grain Structures of Thermal Sprayed Nickel Coatings and the Coating Properties

2005 ◽  
Vol 502 ◽  
pp. 517-0
Author(s):  
Kenji Murakami
Keyword(s):  
Steel Substrate ◽  
Nickel Coatings ◽  
Grain Structures ◽  
Heat Treated ◽  
Columnar Grains ◽  
Different Temperatures ◽  
Plasma Sprayed ◽  
Equiaxed Grains ◽  
Sprayed Coatings ◽  
Lamellar Interfaces

Pure nickel powder was low pressure plasma sprayed onto a steel substrate held at different temperatures during spraying. The as-sprayed coatings consist of columnar grains whose axes are nearly perpendicular to the lamellae composing the coatings. As the coating temperature becomes higher, the length of the columnar grains increases and is longer than the thickness of the lamellae, indicating the growth of the grains across the lamellar interfaces during spraying. On the other hand, the coatings that were heat treated after spraying consist of coarse equiaxed grains. The coatings that experienced high temperatures during spraying or the heat treated coatings have large porosity and contain large globular pores. The hardness, apparent density and the tensile strength of the coating itself were the highest for the coating prepared at a low temperature and became low on heat treatment. The thermal conductivity in the direction perpendicular to the coating was the largest for the coating that consisted of long columnar grains.

scholarly journals Corrosion Resistance of 2060 Aluminum–Lithium Alloy LBW Welds Filled with Al-5.6Cu Wire

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1988 ◽  
Author(s):  
Fencheng Liu ◽  
Xiaoguang Wang ◽  
Baosheng Zhou ◽  
Chunping Huang ◽  
Feiyue Lyu
Keyword(s):  
Intergranular Corrosion ◽  
Laser Beam Welding ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Equiaxed Dendrite ◽  
Al2cu Phase ◽  
Immersion Corrosion ◽  
Aluminum Lithium ◽  
Columnar Grains ◽  
Equiaxed Grains

Alloy sheets of type 2060 aluminum–lithium were welded by laser beam welding (LBW) filled with ER2319 Al-5.6Cu wire. Microstructural observations showed the uneven distribution of columnar grains, equiaxed grains and equiaxed dendrite grains in the weld. The θ′(Al2Cu) phase and other phases precipitated in the weld. The θ′(Al2Cu) phase centrally distributed at the grain boundaries. During the immersion corrosion, the pitting corrosion first occurred and then gradually expanded and transformed to intergranular corrosion and exfoliation corrosion. The electrochemical corrosion test showed a higher corrosion tendency of the base metal and heat-affected zone for the lower corrosion potential, but the corrosion current density of the weld was relatively larger. The segregation of Cu, Mg and other elements at the grain boundary aggravated the occurrence of intergranular corrosion.

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