Critical-current degradation in multifilamentary Nb/sub 3/Al wires from transverse compressive and axial tensile stress

摘要

The effect of transverse compressive stress and axial tensile stress on the critical current of multifilamentary Nb/sub 3/Al superconducting wires has been measured. Compared with commercial Nb/sub 3/Sn, Nb/sub 3/Al exhibits a relatively small sensitivity to both axial and transverse stress. For a given degradation of critical current at 9 T, Nb/sub 3/Al will tolerate about twice as much axial stress as Nb/sub 3/Sn and about five times the transverse stress. The elastic modulus of Nb/sub 3/Al, 169+or-20 GPa, was measured for the first time at cryogenic temperatures and found comparable to that of Nb/sub 3/Sn. A comparison between the effect of axial and transverse stress showed that Nb/sub 3/Al, like Nb/sub 3/Sn, is more sensitive to transverse stress than axial stress. For a given level of critical-current degradation, the transverse stress tolerance of Nb/sub 3/Al is about half the axial stress tolerance. The favorable electromechanical characteristics of Nb/sub 3/Al, compared with Nb/sub 3/Sn, may allow increased operating limits for the next generation of large high-field superconducting magnets.