Failure mechanisms of Al2O3 with different glass phase content at cryogenic temperatures

The effects of glass phase and temperature on the mechanical properties of 99%, 92%, 85% and 75% Al2O3 are investigated. The in-situ XRD results revealed that the lattice constants of Al2O3 single crystals were reduced when temperature decreased from room temperature (RT) to 30 K. The results of mechanical properties were analyzed by Weibull equation. It can be concluded that for the samples containing same content of glass phase, the bending strength and fracture toughness increased as temperature decreased from RT to 77 K. While at the same test temperature, the mechanical properties degraded when the glass phase content increased. The statistical analysis of indentation crack propagation paths of 99% Al2O3 indicated that the proportion of transgranular fracture was increased at 77 K.