Texture in state-of-the-art Nb₃Sn multifilamentary superconducting wires

Abstract

The texture of Nb 3 Sn in recent multifilamentary composite wires has been studied by neutron diffraction, synchrotron x-ray diffraction and electron backscatter diffraction. In powder-in-tube (PIT) type superconductors the Nb precursor filaments exhibit a strong 110 fiber texture as a consequence of the severe cold drawing process, and a 110 texture is also observed in the Nb 3 Sn. In the Nb-Ta precursor of the restacked rod process (RRP) strand there is an additional texture component, and in both Ta-alloyed and Ti-alloyed RRP type conductors the Nb 3 Sn grains grow with a preferential 100 orientation.

Elastic Anisotropy in Multifilament <inline-formula> <tex-math notation="TeX">$\hbox{Nb}_{3}\hbox{Sn}$</tex-math></inline-formula> Superconducting Wires

“…The Nb3Sn elastic anisotropy has been calculated using the grain orientation distribution measured in a PIT wire (billet number B215) produced by Shape Metal Innovation (now Bruker EAS) and in a RRP wire (billet number #7419) produced by Oxford Instruments Superconducting Technology [9]. Cross sections of the PIT wire after 650 °C-120 h heat treatment (HT) and of the RRP wire after 695 °C-17 h HT are shown in Figure 1.…”

“…While in Bronze Route wires the Nb3Sn grains have a nearly random orientation [5,6], we have observed a strong Nb3Sn texture in Powder-in-Tube (PIT) [7] and in Restacked-RodProcess (RRP) type superconductors. As revealed by nondestructive synchrotron X-ray diffraction [8], as well as by Electron Backscatter Diffraction (EBSD) [9], in the PIT wire the Nb3Sn grains have a preferential <110> orientation, while in the RRP wire they have a strong <100> texture.…”

“…Elastic moduli for polycrystalline Nb3Sn have been calculated by averaging the estimates of Voigt and Reuss [10,11] EBSD [9]. Tensile tests of entire PIT and RRP wires and extracted filament bundles have been performed at room temperature (RT).…”

The crystal structure of (Nb0.75Cu0.25)Sn2 in the Cu-Nb-Sn system

“…[20]. The EBSD/EDX investigations were performed on a FEG-SEM LEO 1530 using an electron energy of 20 keV.…”

An experimental and computational study of srain sensitivity in superconducting Nb3Sn

“…In contrast, it was shown by Scheuerlein et al [206] that the grain orientation along the length of a powder-in-tube (PIT) conductor (B215) is preferentially (110) oriented. More recently, an investigation by Scheuerlein et al [207] once again showed that the grain structures of two OST-RRP (billets #7419 and #11976) wires is mainly (100) aligned along the length of the wire, while the grain structure of a PIT wire (B215) is mainly (110) aligned.…”