1. 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein1 Highlights from Bi-2212 Irreversible strain and stress limit of the overpressure processed CDP-CERN Bi-2212 wire produced by OST using Nexans precursor lot 82 Comparison of Bi-2212 electromechanical properties with those of ReBCO and Bi-2223 tapes

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3. EuCARD 2 WP10 meeting C. Scheuerlein3 Use a modified tensile test machine for I c and stress vs strain measurements at 77 K in self-field. Integration in the high energy scattering beamline ID15B of ESRF. XRD in transmission geometry with 86.9 keV photons (absorption in 7 cm of liquid nitrogen is about 50%) Experimental

4. Diffraction pattern of the Bi-2212 wire in ambient air and in liquid nitrogen 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein4 Diffraction pattern of the Bi-2212 wire in air. Diffraction pattern of the Bi-2212 wire in liquid nitrogen.

5. Comparison of Bi-2212 elastic strain, I c, n- value and stress evolution as a function of wire strain A permanent I c degradation of 5% occurs when the Bi-2212/Ag wire strain exceeds 0.61%. Bi-2212 filaments exhibit linear elastic behaviour up to the irreversible strain limit. A drastic drop in I c and n-value occurs at 0.65% strain. At the same strain the wire stress and the Bi-2212 elastic strain reach a plateau. 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein5 Relative I c, n-value, stress and axial Bi-2212 strain variations measured simultaneously at 77 K as a function of the wire strain.

6. Comparison of the electromechanical properties of different HTS: tape and wire characteristics SuperconductorManufacturerTypeCross section (mm 2 ) (c) ReBCO tapeSuperPowerSCS40500.410±0.020 (b) ReBCO tapeAMSCType 87001.95±0.016 (a) B-2223 tape (multifilament)SEIType HT1.64±0.023 Bi-2223 tape (multifilament)SEIType G1.01±0.005 (d) Bi-2212 wire (multifilament)OST37×180.477±0.002 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein6 d

7. Comparison of the 77 K mechanical properties YBCO tapes have high strength because of the high strength of their substrate materials (Hastelloy C276 in the SuperPower and Ni-5 at.% W in the AMSC tape). The non-reinforced and the reinforced Bi-2223 tapes rupture at a strain of roughly 0.2% and 0.4%, respectively. The ultimate strength of the OP processed Bi-2212 wire is comparatively low, but it ruptures at much higher strain than the Bi- 2223 tapes. 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein7

8. Comparison of the irreversible strain limits at 77 K The irreversible strain limit (ε irr-5% ) is defined as the strain at which a permanent I c degradation of 5% occurs. The AMSC ReBCO tape has the highest strain tolerance (ε irr-5% >1%). The SuperPower ReBCO tape and the OP processed Bi ‑ 2212 wire exhibit an irreversible strain limit ε irr-5% of about 0.7% and 0.6%, respectively. The non-reinforced and reinforced Bi-2223 tapes from SEI ruptured at a strain of about 0.2% and 0.4%, without any measurable prior irreversible degradation. 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein8 Comparison of (a) the critical current and (b) n- value variation of different HTS as a function of uniaxial tensile strain.

9. Conclusion I c, stress, and lattice parameters have been measured simultaneously as a function of Bi-2212 wire strain. At 77 K a 5% irreversible critical current degradation of the OP processed Bi-2212 occurs at ε irr-5% =0.60% (  irr-5% ≈ 150 MPa). Up to ε irr-5% the Bi-2212 filaments exhibit linear elastic behaviour. ε irr-5% of the OP Bi-2212 wire is lower than that of the studied ReBCO tapes and significantly higher than that of the reinforced Bi-2223 tape. The relatively high strain tolerance of the Bi-2212 wire may facilitate attempts to increase the irreversible stress limits by wire reinforcements. 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein9

10. Back up slides 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein10

11. Critical current as a function of wire strain 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein11 (a) Self-field critical current at 77 K as a function of the wire strain. (b) Permanent wire elongation after stress relaxation as a function of the maximum wire stress.

12. Comparison of Bi-2212 wire stress and n- value vs strain curves acquired at 77 K 5 June 2015EuCARD 2 WP10 meeting C. Scheuerlein12