Enhancing Transport Performance in 7-filamentary Ba0.6K0.4Fe2As2 Wires and Tapes via Hot Isostatic Pressing

• Published in: Physica. C, Superconductivity Vol. 585; p. 1353870
• Main Authors: Liu, Shifa, Yao, Chao, Huang, He, Dong, Chiheng, Guo, Wenwen, Cheng, Zhe, Zhu, Yanchang, Awaji, Satoshi, Ma, Yanwei
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.06.2021; Elsevier BV
• Subjects: Ba0.6K0.4Fe2As2; Conductivity; Conductors; Copper; Critical current density; Density; Diamond pyramid hardness; Electrical resistivity; Filaments; Hot isostatic pressing; Iron; Iron-based superconductors; Low temperature; Magnets; Mass density; Multi-filamentary wires and tapes; Silver; Studies; Superconducting tapes; Superconductivity; Superconductors; Mass density; Ba0.6K0.4Fe2As2; Multi-filamentary wires and tapes; Hot isostatic pressing; Iron-based superconductors
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2021.1353870

•Seven-filamentary Cu/Ag composite sheathed Ba0.6K0.4Fe2As2 round wires and tapes were fabricated through the PIT method and HIP process with the highest transport Jc up to 4.8 × 104 A cm−2 at 4.2 K and 10 T.•Well-grown plate-like Ba122 grains were obtained as revealed by the SEM observation.•The Vickers hardness measurements indicate that the superconducting filaments in the wires and tapes have a high and rather uniform mass density.•The resistivity measurements show a very low normal-state resistivity at 40 K as a result of the use of copper and silver as the sheath metals. Iron-based superconductors (IBS) are considered as potential materials for manufacturing high-field magnets, for which developing multi-filamentary conductors with high performance and high strength is essential. Herein, 7-filamentary Cu/Ag composite sheathed Ba0.6K0.4Fe2As2 (Ba122) round wires and tapes were successfully prepared through the ex situ powder-in-tube (PIT) method and treated by hot isostatic pressing (HIP) process. Pure Ba122 phase with roughly homogeneous element distribution was obtained in the superconducting filaments. The wires and tapes show very small low-temperature normal-state resistivity of 0.12 μΩ cm and 0.17 μΩ cm respectively owing to the high electrical conductivity of copper and silver. The HIP process greatly enhances the mass density of the superconducting filaments and promotes the formation of well-grown plate-like Ba122 grains. Vickers hardness measurements on the cross sections of these filaments reveal a rather good uniformity of the mass density. The transport critical current density (Jc) in the 7-filamentary Ba122/Ag/Cu round wires and tapes reached 1.3 × 104 A cm−2 and 4.8 × 104 A cm−2 at 4.2 K in 10 T respectively. These results indicate that hot isostatic pressing is advantageous in developing high-performance multi-filamentary iron-based superconductors.