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Dispersion-Strengthened Silver Alumina for Sheathing Bi2Sr2CaCu2O8+x Multifilamentary Wire



Amir Kajbafvala, William Nachtrab, Xifeng Lu, Frank Hunte, Xiaotao Liu, Najib Cheggour, Terence Wong, Justin Schwartz


High strength, high modulus dispersion strengthened (DS) silver-aluminum alloys are studied for sheathing Bi2Sr2CaCu2O8+x (Bi2212) round wire. Dispersion strengthening is an effective method for producing a fine grain metallurgical structure that is resistant to softening during high temperature heat treatment. Here, dispersion strengthened Ag/0.5wt%Al (DS Ag-0.5Al) alloy sheet is produced using powder metallurgy and compared to Ag/0.2wt%Mg alloy, which is currently the most common alloy used for Bi2212 wire. Room temperature, 77 K and 4.2 K tensile tests, Vickers micro-Hardness, optical microscopy, field emission scanning electron microscopy, and electrical resistivity measurements are compared. Furthermore, Bi2212/AgMg and Bi2212/AgAl wires are produced and compared for short-sample and coil Ic(4.2 K, self-field). It is found that DS AgAl solid wire shows high YS and UTS in the annealed condition at both room temperature and 4.0 K, as well as significant ductility at 4.0 K. Electrical transport measurements show that the Bi2212/AgAl wires perform as well or better than Bi2212/AgMg wires. Furthermore, no leakage is observed after partial melt processing (PMP) of Bi2212/AgAl spirals. After PMP, the Bi2212/AgAl wire has yield and tensile stresses slightly higher than Bi2212/AgMg wire, but also exhibits >2 % elongation, which is several times higher than Bi2212/AgMg.
IEEE Transactions on Applied Superconductivity


Dispersion strengthened alloys, Tensile Properties, High Temperature Superconductor, transport measurements


Kajbafvala, A. , Nachtrab, W. , Lu, X. , Hunte, F. , Liu, X. , Cheggour, N. , Wong, T. and Schwartz, J. (2012), Dispersion-Strengthened Silver Alumina for Sheathing Bi2Sr2CaCu2O8+x Multifilamentary Wire, IEEE Transactions on Applied Superconductivity, [online], (Accessed April 15, 2024)
Created January 31, 2012, Updated October 12, 2021