Systematic changes of the Nb-Sn reaction with time, temperature and alloying in Restacked-Rod-Process (RRP) Nb3Sn strands
Reaction heat treatments spanning 605 to 750 C and 24 to {approx}400 hours were applied to several sets of RRP strands. Magnetization and transport measurements were used to track the changes of superconducting properties and the amounts of Nb{sub 3}Sn formed. The experiments showed that temperature increases of 15 C produced equivalent properties in half the time within the temperature range 620-680 C. This result was the same whether Ta or Ti was used to alloy the Nb{sub 3}Sn. The bulk pinning force Fp for Ta-alloyed wires displayed a significant drop for temperatures outside the range above, due to tin gradients at low temperatures and grain growth at high temperatures. The F{sub p} drop at high reaction temperatures prevents wire technology from taking advantage of significantly higher Kramer-plot intercept H{sub K} for high-temperature reactions. On the other hand, Ti alloying provides a quick and potent means to increase H{sub K} at reaction temperatures for which F{sub p} remains high.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 938458
- Report Number(s):
- FERMILAB-PUB-08-304-TD; TRN: US0901805
- Country of Publication:
- United States
- Language:
- English
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