Flexural strength of melt-processed Y-Ba-Cu-O bulk superconductors with Ag addition measured at 77 K

Mechanical properties, such as flexural strength, fracture toughness and ductility, and superconducting properties, T-c, J(c), and H-irr, are crucial for industrial applications of high-T-c oxide superconductors. However, oxide superconductors have the intrinsic brittleness of the perovskite structure, thus the strength and the fracture toughness of the materials are low and anisotropic. Therefore, it is very important to study and improve mechanical properties to achieve structural reliability for applications. Melt-processed REBaCuO (RE = rare earth) superconductors have a high J(c) at 77 K and a high magnetic field, and light rare-earth (LRE) BaCuO has a larger J(c) than YBa2CU3Ox (Y123) in a high magnetic field. High field applications are expected, e.g. a superconducting permanent magnet with liquid nitrogen refrigeration and flywheels. In this paper, we discuss the flexural strength of melt-processed Y123 bulks with Y2BaCuO5 (Y211) particles and Ag measured at 77 K. when the fracture surface is almost perpendicular to the (001) plane. The results show the beneficial effect of Ag particles in the Y123 superconducting phase in strengthening and toughening the material.