Niobium titanium superconducting alloy is one of the most widely used superconducting materials.
Nb-ti alloy with mass ratio of nearly l: 1 has good superconducting electrical properties, and its superconducting critical transition temperature Tc=9. 5K, which can operate at the temperature of liquid helium, under the magnetic field of 5T(50,000 Gs), the transmission current density Jc≥105A/cm2(4). 2 k); The maximum application field can reach 10T(100,000gs)(4. 2 k).
The alloy also has excellent processing properties, which can obtain superconducting wire and strip products through traditional melting, processing and heat treatment.
Therefore, after the research began in the 1960s, it quickly entered the industrial scale production.
The United States produced 100 tons in the late 1970s; China also built pilot production lines around the 1980s.
Practical nb-ti superconducting materials are mostly simple binary alloys, containing 35% ~ 55% Nb. Some tantalum and zirconium can be added to improve superconductivity.
Due to the stability of superconducting, nb-ti superconducting materials are usually pure copper, pure aluminum or cu-ni alloy as the matrix materials, which are embedded with multi-strand nb-ti thin cores to form composite multi-core superconducting materials.
A single superconducting wire can contain tens to tens of thousands of nb-ti cores with a minimum diameter of 1 micron.
In addition, according to the use of different occasions, the multi-core wire is often twisted and transposition, to reduce losses and increase electromagnetic stability.
The basic processing technology of nb-ti superconducting material is as follows: pure titanium and pure niobium are fused into alloy ingots by consumable arc furnace or plasma furnace, and then the bar is formed by hot extrusion and cold drawing. The nb-ti alloy rod was then inserted into the oxygen-free copper tube as the matrix material and composite into a single mandle-rod. And after many times of composite assembly, processed into multi-core nb-ti superconducting wire and strip.
The material needs to be subjected to multiple large cold processing (more than 90% processing rate) and low temperature (less than 400℃) aging heat treatment, so that the superconductor to obtain enough effective binding center, improve the superconducting electrical properties of superconducting materials.
Due to the zero resistance effect of superconductor and the ability of nb-ti superconductor to carry high transport current under strong magnetic field, nb-ti superconductor is particularly suitable for application in electricians with high current and strong magnetic field.
Examples: high field magnets, generators, electric motors, magnetofluid power generation, controlled thermonuclear reactions, energy storage devices, high-speed maglev trains, ship electromagnetic propulsion and transmission cables.
