Open AccessDesign and characterisation of ex situ bulk MgB2 superconductors containing a nanoscale dispersion of artificial pinning centres
Author(s) -
Guillaume Matthews,
Junliang Liu,
C.R.M. Grovenor,
Patrick S. Grant,
Susannah Speller
Publication year - 2020
Publication title -
superconductor science and technology/superconductor science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.033
H-Index - 105
eISSN - 1361-6668
pISSN - 0953-2048
DOI - 10.1088/1361-6668/ab6959
Subject(s) - materials science , ball mill , microstructure , powder metallurgy , sintering , superconductivity , composite number , pinning force , nanoscopic scale , composite material , metallurgy , nanotechnology , condensed matter physics , critical current , physics
MgB 2 pellets containing a nanoscale dispersion of artificial pinning centres have been successfully manufactured through a powder metallurgy route based on the oxide dispersion strengthened (ODS) concept more usually used for steels and superalloys. Commercial MgB 2 powder and Y 2 O 3 nano-powder were mechanically alloyed in a high energy planetary ball mill and consolidated using the field assisted sintering technique. The composite powders were ball milled for different times up to 12 h and characterised by means of particle size analysis, x-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The microstructure and superconducting properties were characterised by density, XRD, STEM and magnetic property measurements. The powder microstructure comprised Y 2 O 3 particles dissolved into the MgB 2 matrix. After consolidation there was a near-uniform dispersion of precipitated YB 4 and MgO particles. A bulk 0.5 wt% Y 2 O 3 -MgB 2 composite showed the best superconducting performance with a significant improvement in J c at high field compared with unmodified MgB 2 , and only a small reduction in T c . The results suggest that the ODS concept is promising to improve the superconducting properties of MgB 2 .