High-temperature deformation of YBa2Cu3O7−δ

Abstract

Steady-state flow stress of dense (99% of theoretical) polycrystalline YBa2Cu3O7−δ has been measured in direct compression at temperatures between 870 and 980 °C in oxygen partial pressures of 0.03, 0.18, and 1.0×105 Pa for strain rates between 5×10−6 and 4×10−5 s−1. The stress exponent was close to one, indicating that diffusional flow was the dominant deformation mechanism. The flow stress decreased with decreasing oxygen partial pressure, obeying a power law with an exponent of approximately 1/2 . The activation energy was about 800 kJ/mol at an oxygen partial pressure 1×105 Pa, but decreased to 600 kJ/mol at a pressure of 3×103 Pa.