High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi2Sr2CaCu2O8+xround wire

Kajbafvala, Amir; Nachtrab, W.T.; Kumar, R. Krishna; Hunte, Frank; Wong, Terence Kin Shun; Schwartz, J.

doi:10.1088/0953-2048/26/12/125012

Cited by 11 publications

(12 citation statements)

References 42 publications

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“…In contrast, the Ag sheathed wires usually need mechanical reinforcement. For example, the stainless steel or Ag0.5 wt%Al alloy sheath have been used in superconducting wires414243, which decrease the engineering J e or increase the complexity and cost of fabrication process. From these view points, we can conclude that the comprehensive performances of our Cu-sheathed Sr-122 tapes are much more attractive for applications than the reported Ag sheathed tapes16171819, demonstrating that Cu is a very promising sheath for the pnictide wires and tapes.…”

Section: Discussionmentioning

confidence: 99%

Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

Lin

Yao

Zhang

et al. 2015

Sci Rep

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Copper sheath is the first choice for manufacturing high-Tc superconducting wires and tapes because of its high electrical and thermal conductivities, low-cost and good mechanical properties. However, Cu can easily react with superconducting cores, such as BSCCO, MgB2 and pnictides, and therefore drastically decrease the transport Jc. Here, we report the fabrication of Cu-sheathed Sr1−xKxFe2As2 tapes with superior Jc performance using a simple hot pressing method that is capable of eliminating the lengthy high-temperature sintering. We obtained high-quality Sr1−xKxFe2As2 tapes with processing at 800 oC for 30 minutes and measured high Tc and sharp transition. By this rapid fabrication, Cu sheath does not give rise to apparent reaction layer, and only slightly diffuses into Sr-122 core. As a consequence, we achieved high transport Jc of 3.1 × 104 A/cm2 in 10 T and 2.7 × 104 A/cm2 in 14 T at 4.2 K. The in-field Jc performance is by far the highest reported for Cu-sheathed high-Tc conductors. More importantly, Cu-sheathed Sr-122 tapes also showed a high Je value of 1.0 × 104 A/cm2 in 10 T at 4.2 K, which has reached the widely accepted practical level for applications. These results demonstrate that Cu is a very promising sheath for the practical application of pnictide conductors.

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Section: Discussionmentioning

confidence: 99%

Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

Lin

Yao

Zhang

et al. 2015

Sci Rep

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“…Bi2212 round wires (RWs) are formed using the powderin-tube (PIT) method with an Ag innermost sheath and either one or two restacks using an oxide-dispersion strengthened (ODS) outer sheath. In most Bi2212 RWs the ODS element is Mg, although recent work has shown significant improvements with the use of Al [15,16]. After deformation to a final diameter, the wires are processed using partial-melt processing (PMP) or variants thereof.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of the relationship between electrical transport and filament microstructure in multifilamentary Bi₂Sr₂CaCu₂O_x/Ag/Ag–Mg round wires

Callaway

Naderi

et al. 2014

Supercond. Sci. Technol.

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After processing, multifilamentary Bi 2 Sr 2 CaCu 2 O x (Bi2212) round wires have complex microstructures. In this study, the microstructures are analyzed quantitatively using a new statistical method in which filaments are categorized based on the predominant phases observed by cross-sectional scanning electron microscopy (SEM). A Matlab program is created to analyze the SEM micrographs and categorize over 100 filaments within the image. In total, 26 wires, each heat treated differently so as to vary the critical current density (J c ), are studied. In some wires, two distinct cross-sectional areas are analyzed, so a total of 41 cross-sections and 5506 filaments are characterized. Five filament types are defined: filaments containing predominantly Bi2212, filaments containing relatively large Bi 2 Sr 2 CuO x (Bi2201) grains, filaments containing relatively large alkaline earth cuprate (AEC) grains but no significant other non-Bi2212 phases, filaments containing relatively large copper-free (CF) grains but no other significant non-Bi2212 phases, and filaments containing relatively large AEC and CF grains. The majority of filaments (78% of all filaments classified) are either predominantly Bi2212 or containing-large-Bi2201 grains. Clear correlations between the number of these two types of filaments and the wire J c are found; J c is directly proportional to the percentage of 'predominantly-Bi2212' filaments. Although typically 70-90% of the containing-large-Bi2201 filament cross-sections is actually Bi2212 phase, J c is inversely proportional to the percentage of this type of filament. Surprisingly, the correlations between J c and the other filament types are weak or non-existent. Furthermore, using high-angle annular dark-field imaging in a scanning transmission electron microscope, Bi2201 intergrowths are found within Bi2212 grains, and results suggest possible differences in the Bi2201 intergrowth densities within Bi2212 grains extracted from predominantly Bi2212 filaments and those from Bi2201-containing filaments. These results indicate that significant enhancements in Bi2212 wire performance require either avoiding the formation of Bi2201, or ensuring complete conversion of Bi2201 to Bi2212.

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“…increase T allowable , one can increase either ε irr or the Young's modulus and/or the yielding stress of the Bi-2212 wire by, for example, using an alternative sheath material such as Ag-Al [25,26].…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…The fast decrease of T allowable with increasing σ a above 120 MPa is a result of the wire starting to plastically deform. Therefore, to increase T allowable , one can increase either ε irr or the Young's modulus and/or the yielding stress of the Bi-2212 wire by, for example, using an alternative sheath material such as Ag-Al [25,26].…”

Section: Analysis and Discussionmentioning

confidence: 99%

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi₂Sr₂CaCu₂O_xmultifilament round wires

Jaroszyński

et al. 2016

Supercond. Sci. Technol.

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The critical current of many practical superconductors is sensitive to strain, and this sensitivity is exacerbated during a quench that induces a peak local strain which can be fatal to superconducting magnets. Here, a new method is introduced to quantify the influence of the conductor stress and strain state during normal operation on the margin to degradation during a quench, as measured by the maximum allowable hot spot temperature T allowable , for composite wires within superconducting magnets. The first conductor examined is Ag-sheathed Bi 2 Sr 2 CaCu 2 O x round wire carrying high engineering critical current density, J E , of 550 A/mm 2 at 4.2 K and 15 T. The critical axial tensile stress of this conductor is determined to be 150 MPa and, in the absence of Lorentz forces, T allowable is greater than 450 K. With increasing axial tensile stress, ! " , however, T allowable decreases nonlinearly, dropping to 280 K for ! " = 120 MPa and to 160 K for ! " = 145 MPa. T allowable (! ") is shown to be nonlinear and independent of magnetic field from 15 T to 30 T. T allowable (! ") dictates the balance between magnetic field generation, which increases with the magnet operating current and stress, and the safety margin, which decreases with decreasing T allowable , and therefore has important engineering value. It is also shown that T allowable (! ") can be predicted accurately by a general strain model, showing that strain control is the key to preventing degradation of superconductors during a quench.

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High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

Cited by 11 publications

References 42 publications

Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

Statistical analysis of the relationship between electrical transport and filament microstructure in multifilamentary Bi₂Sr₂CaCu₂O_x/Ag/Ag–Mg round wires

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi₂Sr₂CaCu₂O_xmultifilament round wires

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High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi2Sr2CaCu2O8+xround wire

Cited by 11 publications

References 42 publications

Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

Statistical analysis of the relationship between electrical transport and filament microstructure in multifilamentary Bi2Sr2CaCu2Ox/Ag/Ag–Mg round wires

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi2Sr2CaCu2Oxmultifilament round wires

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High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi₂Sr₂CaCu₂O_8+xround wire

Statistical analysis of the relationship between electrical transport and filament microstructure in multifilamentary Bi₂Sr₂CaCu₂O_x/Ag/Ag–Mg round wires

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi₂Sr₂CaCu₂O_xmultifilament round wires