New nanoscale artificial pinning centres for NbTi superconductors. (15th January 2021)

• Record Type: Journal Article
• Authors: Mousavi, Tayebeh; Grant, Patrick S.; Speller, Susannah C.; Grovenor, Chris
• Is Part Of: Materials & design. Volume 198(2021)
• Publication Date: 2021-01-15
• Subjects: Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2020.109285
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: The efficiency of new artificial pinning centres have been investigated in NbTi using the oxide dispersion strengthening (ODS) concept more typically applied to steels and Ni-superalloys. NbTi alloys containing a dispersion of nanoscale Y2 Ti2 O7 particles have been successfully manufactured through a powder metallurgy route by mechanical alloying Nb, Ti and Y2 O3 nanopowders using high energy ball milling and subsequent consolidation and annealing. The microstructure and superconducting properties of the NbTi-Y2 O3 have been characterised after each processing step. After 40 h of ball milling, the Y2 O3 particles are dissolved into the nanostructured NbTi matrix formed by mechanical alloying of Nb and Ti. On annealing at temperatures above 800 °C the dissolved Y and O react with Ti from the matrix, and fine Y2 Ti2 O7 particles (<5 nm) are precipitated. These NbTi-Y2 Ti2 O7 composites showed excellent superconducting performance, with JC of 5.2 kAmm −2 at 4.2 K, 5 T, considerably higher than Y2 O3 -free bulks manufactured using the same process and NbTi wires manufactured using the conventional thermomechanical process. The results suggest that ODS powder processing is a promising new route to manufacture NbTi alloys containing artificial pinning centres that give superior superconducting properties. Graphical abstract: Unlabelled Image Highlights: Superconducting NbTi bulks with improved current densities were fabricated by new processing routes. New artificial pinning centres of Y2 Ti2 O7 nanoparticles (<5 nm) have been developed in NbTi superconducting bulks. Y2 Ti2 O7 nanoparticles show different pinning mechanisms from those of α-Ti known as pinning centres in NbTi for many years.