Characterization of Electromechanical Properties in Differently Sheathed MgB2 Wires Under Uniaxial Tension

In this study, the electromechanical properties of the differently sheathed 18 module MgB
₂
wires were evaluated under uniaxial tensile loading at 20 K and 2 T. Four kinds of 18 module MgB
₂
wire samples with different configurations were used. They have Cu sheath/Nb barrier/MgB
₂
filament structure with different ratio of non-SC/SC or different sheath materials. The mechanical and electromechanical properties of the MgB
₂
wires at 20 K and 2 T were examined using the Katagiri-type test probe. At 20 K, as the applied magnetic field increased, all MgB
₂
samples showed a significant
I_c
degradation but the same
I_c
(
B
) dependence was observed regardless of the sheath configuration. Monel sheathed sample 4 exhibited the highest yield strength and elastic modulus,
σ_y
= 634 MPa and
E
= 178 GPa at 20 K, respectively. Both samples 2 and 3 which had a lower non-SC/SC ratio by additional etching process exhibited a higher irreversible strain limit
ϵ
_irr
= 0.30%.