Understanding the performance limits of Nb3Sn superconducting wire is important to the design of superconducting magnets. Measuring these limits, however, is complicated by local chemical variations (on the scale of ∼1 μm) in superconducting properties due to inhomogeneity in the wires. We have fabricated 1 mm3, homogeneous, binary Nb3Sn samples using hot isostatic pressing techniques on powder‐in‐tube bulk samples. The effects of Sn concentration and of Sn gradients on critical temperature (Tc) and the measured upper critical field (μ0Hc2) were examined using high sensitivity magnetometry. μ0Hc2(0) varies linearly from 10.9 Tesla (T) at 19.3 at.% Sn to 31.4 T at 24.6 at.% Sn. The latter is an extraordinarily high value, suggesting that the Cu present in all practical Nb3Sn conductors may actually suppress Hc2. Additionally, we demonstrate conclusively the propensity for stoichiometric Nb3Sn to form below 1800°C, even when the nominal composition is decidedly off‐stoichiometric. This shows the need for a fully volumetric measurement to accurately assess the effects of chemical inhomogeneity. Quantifying μ0Hc2(%Sn) sheds light on the fundamental performance limits of Nb3Sn and quantifies the material property loss due to the inhomogeneous nature of all commercial Nb3Sn wires.
|Name||AIP Conference Proceedings|
|Conference||2003 Cryogenic Engineering Conference and International Cryogenic Materials Conference, CEC/ICMC 2003|
|Period||22/09/03 → 26/09/03|