Manufacture of practical NbTi alloy superconductor

(1) Alloy smelting. The optimum alloy ratio contains titanium in 46%~50%(mass percentage).
(2) NbTi alloy rod processing, high uniform NbTi rod in addition to uniform composition, but also the uniformity of mechanical properties.
(3) Coated stabilization material, so that hundreds of NbTi wires buried in the stabilization role of high conductivity oxygen-free copper or high purity aluminum, in order to prevent heat loss or provide current bypass. Residual resistivity ratio (RRR) is often used to illustrate the quality of stabilized materials. RRR refers to the ratio of the resistivity at room temperature of 293K divided by the resistivity at low temperature (4.2K). Usually, superconducting magnets require the RRR ratio of stabilized materials to be 30 or above.
(4) package blocking material. niobium is a kind of barrier material widely used in order to avoid the formation of Intermetallic compounds such as TiCu4 between NbTi alloy and Cu matrix, and to prevent the cable from breaking the core and significantly reduce the critical current density (Jc).
(5) The composite design of multi-core complex, the composite design is carried out before hot extrusion, the design is based on the parameter requirements of the finished superconducting line, such as wire diameter, core diameter, copper ratio, etc., to calculate the size of the sheath barrier layer, NbTi rod and the number of extrusion. Multi-core composite line in the NbTi core wire is closely arranged, from the core to the outside are arranged by the hexagonal layer, the root number of each layer in turn constitute the relation of the arithmetic series, such as 6, 12, 18, 24, 30, 36... .
(6) extrusion and stretching, using extrusion to make NbTi bar, Nb barrier layer and Cu layer matrix between the formation of high bonding strength of gold.