Electromechanical Properties of Filamentary $ \hbox{MgB}_{2}$ Wires

This work describes the performance of several
$\hbox{MgB}_{2}$
composite wires when subjected to tensile stress at 4.2 K. Electromechanical properties of these wires are influenced by the composite elements encasing the filament and also by the filament's mechanical strength. A linear increase in critical current by tension up to
$\approx$
20% was measured due to compensation of the precompression effect caused by different thermal expansions of composite elements. Final heat treatment influences the electromechanical characteristics of composite wires due to stress recovery and also by interface reactions among the composite elements. Results showed that the highest irreversible strain
$\varepsilon_{\rm irr} = 0.9 \%$
was obtained for
$\hbox{MgB}_{2}$
wires reinforced by stainless steel, which has more than doubled
$\varepsilon_{\rm irr}$
in comparison to commercially available
$\hbox{MgB}_{2}/\hbox{Nb/Cu/Monel}$
wires with the same filament number.