The influence of HIP on the homogeneity, Jc, Birr, Tc and Fp in MgB2 wires

Abstract

Unreacted MgB2 wires were made at Hyper Tech Research, USA by a continuous tube forming and filling method using mixtures of Mg and B with and without SiC powder additions. All of the wires underwent hot isostatic pressure (HIP) treatment at the Institute of High Pressure. The first part of the wire was annealed at a pressure of 1 GPa, and the second part was annealed at 0.1 MPa. In this work, we show the influence of high pressure on critical current density (Jc), pinning force (Fp), critical temperature (Tc), irreversible magnetic fields (Birr) and the Fp scaling and microstructure of MgB2 wires. The results obtained indicate that after annealing at high pressure, the MgB2 wires show increases of Jc and Fp in high magnetic fields (8 T–12 T); in SiC doped MgB2 wires, Fpmax shifts to higher magnetic fields. We also compared the Jc of the doped and undoped MgB2 wires (without HIP and with HIP). The scanning electron microscope (SEM) results show that HIP increases the density of MgB2 material and improves its uniformity.