Mechanical reliability of high Tc superconductors

This paper reviews the current research on the strength and fracture toughness of high Tc oxide superconductors. A fracture mechanics framework is presented as a background to the experimental measurements. The various factors which influence mechanical reliability are discussed. Data presented on both single crystals and polycrystalline superconductors indicate that the resistance to crack growth in Ba-Y-Cu-O materials is intrinsically very small, leading to low strengths. In addition, it is shown that fracture of these materials is sensitive to moisture which further reduces strengths, especially under long term loads.