Single- and 4-core MgB2 composites were made by using the powder-in-tube method, with commercial MgB2 powder in an Fe sheath. The transport currents of as-deformed wires were measured at 4.2K in external magnetic fields, B, of 0 to 4T. Different JC(B) curves were observed for single- and 4-core wires; depending upon the value of the self-field current. The behavior of JC(B) and JC(α) was influenced by Fe sheath magnetization by self-field and external field. Field distribution and IC(B) curves were calculated by using the finite element method, and were used to explain the experimental characteristics.

The Effect of Fe-Magnetization on IC(B) and IC(α) Characteristics of Iron-Sheathed MgB2 Composite Wires. P.Kovác, M.Ahoranta, T.Melišek, J.Lehtonen, I.Hušek: Superconductor Science and Technology, 2003, 16, 793-8