MECHANICAL CHARACTERIZATION OF TOP-SEEDED MELT-TEXTURED YBA2CU3O7-DELTA SINGLE-CRYSTAL

The development of high J(c) superconductors for high magnetic field a pplications has identified the limiting problem of mechanical stabilit y of the superconductor under high applied magnetic field. The flaw, c rack and pore distribution in unannealed, annealed and avalanched, top -seeded, melt-textured YBCO disks were characterized. Flexural strengt h and fracture toughness of these three conditions provided sufficient data for an estimation of critical flaw size. The fracture surface an d crack path were also observed by SEM methods to identify the growth character of cracks.