Tensile fatigue behavior and crack growth in GdBa ₂ Cu ₃ O 7− x /stainless-steel coated conductor grown via reactive co-evaporation

Abstract (RE)Ba 2 Cu 3 O 7− x (REBCO) conductors have the potential to enable a wide range of superconducting applications over a range of temperatures and magnetic fields (Vincent et al 2013 IEEE Trans. Appl. Supercond. 23 5700805 ), yet AC applications and devices with a charge/discharge cycle may be limited by the conductor fatigue properties. Here the fatigue behavior of GdBa 2 Cu 3 O 7− x (GdBCO) conductors grown by reactive co-evaporation on stainless-steel substrates is reported for axial tensile strains, ε , up to 0.5% and 100 000 cycles. Failure mechanisms are investigated via microstructural studies and compared with a commercially available IBAD/MOCVD REBCO conductor. Results show that GdBCO/stainless-steel conductors retain their transport critical current for 10 000 cycles at ε = 0.35% and ε = 0.45%, and for 1000 cycles at ε = 0.50%. The main cause of fatigue degradation in GdBCO conductors is crack propagation and delamination that initiates at the edge of the conductor due to manufacturing defects.