Effects of wire diameter, tape thickness, and rolling ratio on the superconducting properties of monocore Fe/MgB2 conductors

In this work, we studied the superconducting properties of MgB2 monocore iron sheathed wires of different diameters and tapes of different thicknesses produced using the in-situ powder-in-tube (PIT) method. We manufactured wires and tapes using the in-situ PIT method by filling the iron tube with previously prepared unreacted Mg and 2B powder. Thus, the 15 mm diameter tube underwent a groove rolling process to reduce its diameter to 3 mm to produce wires. In addition, the wires were subjected to cold drawing and were cut with diameters of 2.5 mm, 2.0 mm, 1.7 mm, and 1.3 mm. Therefore, these wires with different diameters were subjected to a flat rolling process to produce tapes, and parts of the tape sample were cut with different thicknesses of 1.2 mm, 0.9 mm, 0.6 mm, and 0.4 mm. During these processes, the wires and tapes were subjected to intermediate heat treatments at a temperature lower than the synthesis temperature of MgB2 to reduce the mechanical stress due to these processes. After these steps, heat treatment was carried out at 700°C for 2 hours using a tube furnace. We have examined the effects of electrical / superconductivity for all samples. Temperature-resistance and current-voltage measurements were made using a cryostat system at magnetic fields of up to 7 Tesla by cutting samples with a length of 25 mm from the middle part of our samples. The results indicate that the tape sample that is 1.2mm thick is flat rolled from wire with diameters of 2.0mm and possesses the most suitable properties for superconducting than the tape samples due to its higher Tc at 37.76K. The most important result is that the wire sample with a diameter of 1.7mm shows the highest Tc among the wire and tape samples at 37.87K. On the other hand, Tapes of smaller thickness show faster degradation of Je, which makes them less suitable for applications involving strong magnetic fields.