Mechanical properties and strain effects in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x//AgMg composite conductors

The development of powder-in-tube Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ technology has progressed such that high critical current density (J/sub c/) conductors are produced by many researchers, Prototype systems are being tested to demonstrate engineering feasibility. An important issue that remains, however, is the effect of mechanical strain. While it is evident that large strains induce irreversible damage, applications may be limited by fatigue at low strain values due to crack propagation. Here we report on the development of two devices designed specifically to study strain effects in high temperature superconducting tapes. Preliminary results of the effects of cyclic fatigue on J/sub c/ of AgMg-clad Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/, as measured by electrical transport is shown. Measurements of the constituent and composite mechanical properties are also reported.