Role of Cr-coating by electroplating method on fabrication and transport properties of Fe/Cr/MgB2 wires

This study has focused on the use of chromium metal as a chemical barrier in the production of in situ MgB2 wires. The chromium metal was plated homogeneously into the initial iron tube by electroplating in order to produce in situ mono-core and multi-filamentary Fe/Cr/MgB2 wires. Cr metal has maintained its continuity through the wire drawing, but inhomogeneous thickness of Cr-coating at the Cr/Fe interface region without chemical reaction to each other is revealed. The in situ mono-core Fe/Cr/MgB2 wire with a diameter of 1.32 mm and multi-filamentary wires with 1.00 mm and 1.26 mm diameters were produced by PIT process and heat treated at different annealing temperatures and times. Transport and structural investigations of the wires indicated locally positive effect of Cr-coating on Fe2B phase formation, transport properties, and the core structure of MgB2 wires. The mono-core Fe/Cr/MgB2 wire-coded A24 has the highest engineering critical current density of 56 A/cm(2) at 30 K under 6.5 T.