CHARACTERIZATION OF THE DENSIFICATION OF ALUMINA BY MULTIPLE SMALL-ANGLE NEUTRON-SCATTERING

Multiple small-angle neutron scattering was used to follow the evolution of the pore-size distribution in alpha-Al2O3 through the intermediate and final stages of sintering. This new technique enables the study of microstructure in the 0.08-10 mu-m size regime, which is the size range of importance for many materials systems, without needing to increase the resolution of currently available small-angle scattering instruments. The microstructure evolution results indicate a nearly constant effective pore radius for the alumina throughout the intermediate sintering stage, ranging from 0.19-mu-m at 54% of theoretical density to 0.17-mu-m at 79% dense. As the alumina densifies further, there is a transition region after which the effective pore radius grows rapidly to greater-than-or-equal-to 0.6-mu-m at 97.5% dense.