Study of liquid-infiltrated Nb-Sn superconducting composite wire by specific heat measurements.
01 January 1986
The results of specific heat and inductive T(c) measurements on reacted liquid-infiltrated superconducting composite wires with an overall composition of Nb-8 at.% Sn are presented. It is found that approximately 23 wt.% of the reacted wire is high T(c) A15 phase, a result not expected from the equilibrium phase diagram. The relatively sharp superconducting transition at 18K is indicative of a uniform stoichiometric Nb-25 at.% Sn composition in the A15 phase. The large fraction of high T(c) material in these wires is due to taking advantage of the rapid diffusion of Nb in liquid Sn. From a detailed analysis of the specific heat, comments on the reaction process are made. Implications for the equilibrium phase diagram are discussed.