Title :
Improved superconducting Nb/sub 3/Sn wire using Nb(Ti), Sn(Ga), Cu, and Ag powders
Author :
Thieme, C.L.H. ; Foner, S.
Author_Institution :
Francis Bitter Nat. Magnet Lab., MIT, Cambridge, MA, USA
fDate :
3/1/1993 12:00:00 AM
Abstract :
Superconducting Nb/sub 3/Sn wire was produced by means of the powder metallurgy process using Nb-2.9 at.% Ti and Sn-6.2 at.% Ga powders to which small quantities of Cu, Ag or Cu+Ag powders were added. Using heat treatments at 950 degrees C and 750 degrees C, these additions increased the overall critical current density to 10/sup 8/ A/cm/sup 2/ at 22.8 T and 4.2 K. B/sub c2/ versus T measurements showed an increase in B/sub c2/ at temperatures of 6-18 K, of about 1 T, and T/sub c/ was increased by about 0.4 K. In a different wire annealed in a U-shape, the overall J/sub c/ at 23.5 T was 0.5*10/sup 8/ A/m/sup 2/ at 4.2 K, 1.4*10/sup 8/ A/cm/sup 2/ at 2.5 K, and 1.9*10/sup 8/ A/m/sup 2/ at 1.6 K. n-values were measured at fields up to 23 T. The different chemical activities of Ga and Sn when dissolved in Cu are discussed.<>
Keywords :
critical current density (superconductivity); niobium alloys; superconducting transition temperature; tin alloys; type II superconductors; 750 degC; 950 degC; critical current density; powder metallurgy; superconducting Nb/sub 3/Sn wire; Annealing; Critical current density; Current measurement; Density measurement; Heat treatment; Niobium; Powders; Superconducting filaments and wires; Temperature; Tin;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
