Role of Interfacial Defect Creation-Annihilation Processes at Grain Boundaries on the Diffusional Creep of Polycrystalline Alumina

Abstract

It is generally assumed in the diffusional creep of a polycrystalline solid that grain boundaries act as perfect sources and sinks for lattice defects. However, if this assumption is not valid, then diffusional creep can become rate limited by interfacial defect reactions at grain boundaries1–2 Steady state diffusional creep data will be presented at 1450–1500°C for polycrystalline alumina doped with Ti and a Mg-Ti co-dopant, which are consistent with interfacial controlled kinetics over an intermediate grain size range. A new type of creep deformation map will be presented which reveals the range of grain sizes and impurity concentrations over which interfacial defect creation and/or annihilation processes are important in the steady state creep of polycrystalline alumina.