Evolution of Electromagnetic Properties and Microstructure With Sintering Temperature for ${\hbox {MgB}}_{2}/{\hbox {Fe}}$ Wires Made by Combined In-Situ/Ex-Situ Process
The influences of microstructure, connectivity, and disorder on the critical current density, <i>J</i><sub>c</sub>, are discussed to clarify the different mechanisms of <i>Jc</i>(<i>H</i>) in different magnetic field ranges for in-situ and combined in-situ/ex-situ MgB<sub>2</sub>/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, <i>H</i><sub>c2</sub> , and irreversibility field, <i>Hirr</i>, are studied to demonstrate the mechanism of J<sub>c</sub> dependence on magnetic field. The combined in-situ/ex-situ process is proved to be a promising technique for fabrication of practical MgB<sub>2</sub> wires.