Development of high performance multifilamentary Nb-Ti-Ta superconductor for LHC insertion quadrupoles

Author

Lee, P.J. ; Fischer, C.M. ; Larbalestier, D.C. ; Naus, M.T. ; Squitieri, A.A. ; Starch, W.L. ; Werner, J. ; Limon, P.J. ; Sabbi, C. ; Zlobin, A. ; Gregory, E.

Author_Institution

Appl. Supercond. Center, Wisconsin Univ., Madison, WI, USA

Volume

9

Issue

2

fYear

1999

fDate

6/1/1999 12:00:00 AM

Firstpage

1571

Lastpage

1574

Abstract

A preliminary investigation of a new Nb-Ti-Ta (39 wt.%Nb, 44 wt.%Ti, 17 wt.%Ta) alloy has been investigated as a possible material for application at 1.9 K and 10.5 T in the insertion quadrupoles of LHC, 1550 A/mm/sup 2/, the highest yet reported critical current density at 10.5 T (1.9 K), was achieved in a monofilament of this material. The initial multifilamentary production strand produced a lower 10.5 T (1.9 K) critical current density of 1370 A/mm/sup 2/. Large variations in precipitate size were produced in the microstructures, which have yet to be fully optimized. Quantitative analysis of the microstructures in a Nb-44 wt.%Ti-15 wt.%Ta alloy reveals a linear relationship between volume % of /spl alpha/-Ti precipitate and critical current density at 5 T and 8 T (4.2 K). The increase in critical current with precipitate volume is less than for Nb-47 wt.%Ti. High resolution FESEM electron backscatter images suggest a high atomic number region adjacent to the grain boundaries after heat treatment.

Keywords

accelerator magnets; critical current density (superconductivity); crystal microstructure; field emission electron microscopy; grain boundaries; multifilamentary superconductors; niobium alloys; precipitation; scanning electron microscopy; superconducting magnets; tantalum alloys; titanium alloys; type II superconductors; /spl alpha/-Ti precipitate; 1.9 K; 10.5 T; LHC insertion quadrupoles; Nb-Ti-Ta; critical current density; grain boundaries; heat treatment; high atomic number region; high performance multifilamentary Nb-Ti-Ta superconductor; high resolution FESEM electron backscatter images; multifilamentary production strand; precipitate size; precipitate volume; quantitative analysis; Backscatter; Critical current; Critical current density; Electrons; Grain boundaries; Heat treatment; Image resolution; Large Hadron Collider; Microstructure; Production;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.784695

Filename

784695