Evolution of electromagnetic properties and microstructure with sintering temperature for MgB2/Fe wires made by combined in-situ/ex-situ process

The influences of microstructure, connectivity, and disorder on the critical current density, Jc, are discussed to clarify the different mechanisms of Jc (H) in different magnetic field ranges for in-situ and combined in-situ/ex-situ MgB2/Fe wires. Sintering temperature plays a very important role in the electromagnetic properties at different temperatures and under various magnetic fields. Connectivity, upper critical field, Hc2, and irreversibility field, Hirr, are studied to demonstrate the mechanism of Jc dependence on magnetic field. The combined in-situ/ex-situ process is proved to be a promising technique for fabrication of practical MgB2 wires.