Effect of Heat Treatment on Superconducting Properties of Pure and Ti, Zr-doped MgB2 Superconducting Wires Fabricated by In-situ PIT Method

摘要

Dense MgB_2 wires were successfully fabricated through the in-situ powder-in-tube (PIT) method by using steel sheath with low carbon content. Short samples of MgB_2/Fe wires were sintered at 650-850 °C for 2-5 hours in argon. Critical current density( J_c) of the wires was measured at 4.2K in the magnetic field up to 8 T by standard four probe method. High J_c values of 2.1 × 10~5A/cm~2 in 3T at 4.2K were obtained for MgB_2/Fe wires. The microstructure observation for MgB_2 wires showed that no reaction between Fe and MgB_2 was found and MgB_2/Fe wires had better grain connectivity. The results indicated that the J_c can be further improved to meet the requirement for applications by optimizing the process conditions.