2014
DOI: 10.1088/0953-2048/27/9/095009
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Influence of heat treatment temperature and Ti doping on low-field flux jumping and stability in (Nb-Ta)3Sn strands

Abstract: The impacts of heat treatment (HT) temperature and Ti doping on low-field flux jumping and 12 T J c of high-performance internal-Sn, distributed barrier (Nb-Ta) 3 Sn strands have been explored. It was found that higher HT temperatures could suppress low-field flux jumps by not only reducing the J c (B) curve slope, but also increasing the heat capacity and decreasing the dJ c / dT. A metric, J c,3 T /J c,12 T (the ratio of 3 T to 12 T J c ), was used to describe the slope of the J c (B) curve. In addition, an … Show more

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Cited by 18 publications
(30 citation statements)
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“…Further improvements are being pursued. respectively, which are about half of those RRP and PIT wires reacted at 650-675 °C [4,30], but much larger than the average grain sizes of the early APC samples with 1% Zr and sufficient O reacted below 650 °C, which were 35-45 nm [15,19,20]. For APC-A, this is because it was reacted at 675 °C and it had only 0.6%Zr in the Nb alloy: lower Zr content leads to fewer ZrO2 particles for grain refinement.…”
Section: Resultsmentioning
confidence: 99%
“…Further improvements are being pursued. respectively, which are about half of those RRP and PIT wires reacted at 650-675 °C [4,30], but much larger than the average grain sizes of the early APC samples with 1% Zr and sufficient O reacted below 650 °C, which were 35-45 nm [15,19,20]. For APC-A, this is because it was reacted at 675 °C and it had only 0.6%Zr in the Nb alloy: lower Zr content leads to fewer ZrO2 particles for grain refinement.…”
Section: Resultsmentioning
confidence: 99%
“…Doping to Nb3Sn can be controlled via the additions to the precursors (e.g., Nb-7.5wt.%Ta, Nb-47wt.%Ti, or Sn-Ti), which is mature for present conductors. On the other hand, high Sn content typically requires high heat treatment temperature (e.g., Figure 5) which is undesirable as grain size increases exponentially with reaction temperature [55]. Evidently a fundamental understanding of what controls Nb3Sn stoichiometry is critical.…”
Section: A Theory For Nb3sn Stoichiometrymentioning
confidence: 99%
“…Heat treatment temperature can simultaneously influence multiple factors, such as chemical potential of Sn in the Sn source, diffusion rate of Sn in Nb3Sn, and reaction rates at Another factor that may influence the Sn content of Nb3Sn, according to the above theory, is the competition between the Sn diffusion rate across the Nb3Sn layer and the Nb-Sn reaction rate at the Nb3Sn/Nb interface. This effect has hardly been noticed; however, the phenomenon that Ti addition tends to accelerate Nb3Sn layer growth rate [55] and make the stoichiometry more uniform in the Nb3Sn layer [73] could be explained by this effect. It has been seen that Ti addition segregates at Nb3Sn grain boundaries and causes greater lattice distortion at grain boundaries, which is believed to cause higher grain boundary diffusivity [84].…”
Section: A Theory For Nb3sn Stoichiometrymentioning
confidence: 99%
“…For Nb 3 Sn, improvement in critical current density can be realized by refining grain size . Present day Nb 3 Sn strands have average grain sizes of typically 100–200 nm .…”
mentioning
confidence: 99%