Chishko V. Modification of structure and properties of NbTi superconductors using the equal-channel multi-angle pressing

Object: the process of modification of structure and properties of low-temperature superconductors on the base of NbTi alloys. The purpose: the determination of the formation laws of structural, physical, mechanical and functional properties of NbTi superconductors at intensive plastic deformation with application of equal-channel multiangular pressing for working out of physical and technological bases of advanced technology of their manufacturing. Methods: x-ray structural analysis, optical, raster, transmission electronic and ionic microscopy; microhardness indentation, mechanical tests, measurements of density, electric resistance, magnetization and a critical current. Results: For the first time the possibilities of structure and properties of NbTi superconductors modification with use of intensive plastic deformation by a method of equal-channel multiangular pressing are investigated. It is shown, that the inclusion of equal-channel multiangular pressing in the traditional scheme of processing of superconductors leads to formation of high-homogeneous nanostructure with the diffuse texture and the big density of grain boundaries. It is established, that in NbTi alloys, preliminary subjected to equal-channel multiangular pressing, at the next deformation-thermal processing the acceleration of beta-phase disintegration with allocation of alpha-phase processes take place. As a result the considerable (to two times) increase of a critical current density and also the increase of relative elongation at ultimate stress limit preservation is observed. Field of application: physics of a solid state, the physics of durability and plasticity, the physicist of metals, superconductivity