Microfilamentary superconducting composites by the external diffusion method: Nb3Sn

摘要

Microfilamentary superconducting composites of Nb3Sn fibers in bronze matrices were produced by the external diffusion method together with a solution preanneal to suppress Kirkendall porosity. The resulting materials had superior superconducting and mechanical properties at 4.2 °K, carrying overall current densities well over 104 A/cm2 at 15.4 T even for low (12%) superconductor fractions; over 105 A/cm2 at 12 T; and tolerating (in some cases) strains of the order of 2% without degradation, and stresses in the 500–1000 MPa range. There is evidence that finer superconducting filaments can tolerate much greater intrinsic strains without degradation; also, that the composites investigated were not optimized in terms of residual stresses, matrix composition, or filament spacing or size, so that further improvements are possible.