Preparation of MgB2/Fe tapes with improved Jc property using MgH2 powder and a short pre-annealing and intermediate rolling process

Abstract

A short pre-annealing and intermediate rolling process was applied to in situ processedMgB2/Fe tapes preparedusing MgH2 and Bpowders. The Jc properties of both the non-doped and 10 at.% nano-SiC-dopedMgB2/Fe tapes were greatly improved by this modified in situ process. The bestJc results were obtained in the samples pre-annealed at600 °C for 15 min and furtherheat treated at 600 °C for 1 h after the intermediate rolling. An enhancement of about 80% inJc values in 10 T and at 4.2 K was achieved for both SiC-doped andnon-doped tapes using this optimum condition. The decomposition ofMgH2 at the early reaction stage would generate many cracks and pores,which leaves a porous core in the tapes before the formation ofMgB2. In our modified in situ process, the decomposition ofMgH2 was completed within a 15 min pre-annealing at600 °C;the MgH2-decomposition-generated pores and cracks were effectively eliminated by the subsequentrolling. The core densities of the final tapes were significantly enhanced by utilizingthis pre-annealing and intermediate rolling process, which in turn improved theJc propertyof the MgB2 tapes.