Improvement of Reversible Strain Limit for Critical Current of DI-BSCCO Due to Lamination Technique

The DI (dynamically innovative)-BSCCO-Bi2223 tapes achieved high critical current as well as high modulus of elasticity. Further the reversible strain limit and the corresponding stress for critical current have been remarkably increased by means of lamination technique. During the course of development, their optimized architecture has been designed based on the principle of the rule of mixture for maximizing the force free strain exerted on the superconducting component. The reversible strain/stress limit (A _rev/R _rev) was defined as a strain, at which the critical current recovers to the level of 99% I _co. Selecting several kinds of laminating materials and changing condition of the fabrication, the excellent Cu alloy-3ply tape with I _co of 311 A/cm was realized of which A _rev and R _rev reached 0.42% and 300 MPa, respectively. Further during the theoretical analysis, the increase of reversible strain limit were made clear to be attributed to the increase of thermally induced residual strain as well as the compensation effect of laminated layers against a local fracture mode.