Creep behaviour of alumina/YAG nanocomposites obtained by a colloidal processing route

摘要

The high temperature creep behaviour (1200-1400 deg C and 30-250MPa) of high-purity alumina (A) and an alumina/YAG nanocomposite (AY) prepared by using a colloidal processing route has been studied. Creep parameters were correlated with microstructural features in order to determ' the dominant creep mechanisms in both materials. It was found that the creep rate value of AY was 1 order of magnitude lower than the one of undoped alumina A. The creep mechanism for AY was found to be lattice diffusion (Nabarro-Herring) compared to a combination of grain boundary (Coble) and lattice diffusion for A When the slow crack growth region of both materials was compared, a significant improvement was observed, i.e. the slow crack growth region of alumina shifted to nearly 2.5 times the stresses applied for AY at the temperatures of 1200, 1300 and 1400 deg C.