Niobium–titanium is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets, normally as Nb-Ti fibres in an aluminium or copper matrix. Its critical temperature is about 10 kelvins. In 1962, at Atomics International, T. G. Berlincourt and R. R. Hake, discovered the superior high-critical-magnetic-field, high-critical-supercurrent-density properties of Nb-Ti that, together with affordability and easy workability, distinguish Nb-Ti alloys from thousands of other superconductors and justify their status as the most widely utilized superconductors. With a maximal critical magnetic field of about 15 teslas, Nb-Ti alloys are suitable for fabricating supermagnets generating magnetic fields up to about 10 teslas. For higher magnetic fields, higher-performance, but more expensive and less easily fabricated superconductors, such as niobium-tin, are commonly employed. The part of global economic activity for which superconductivity is indispensable amounted to about five billion euros in 2014. MRI systems, most of which employ niobium-titanium, accounted for about 80% of that total.
Notable uses
Superconducting magnets
A bubble chamber at Argonne National Laboratory has a 4.8-meter-diameter Nb-Ti magnet producing a magnetic field of 1.8 tesla. About 1000 NbTi SC magnets were used in the 4-mile-long main ring of the Tevatron accelerator at Fermilab. The magnets were wound with 50 tons of copper cables containing 17 tons of NbTi filaments. They operate at 4.5 K generating fields up to 4.5 tesla. 1999: The Relativistic Heavy Ion Collider uses 1,740 NbTi SC 3.45 tesla magnets to bend beams in its 3.8 km double storage ring. In the Large Hadron Colliderparticle accelerator the magnets are cooled to 1.9 K to allow safe operation at fields of up to 8.3 T. Niobium–titanium superconducting magnet coils were built to be used in the Alpha Magnetic Spectrometer mission to be flown on the international space station. They were later replaced by non-superconducting magnets. The experimental fusion reactorITER uses Niobium–titanium for its poloidal field coils. In 2008 a test coil achieved stable operation at 52 kA and 6.4 Tesla. The Wendelstein 7-X stellarator uses NbTi for its magnets, cooled to 4 K to create a 3 tesla field.
