Thermal grooving and migration of grain boundaries in alumina were investigated using a variety of microscopy techniques. Using two different methods, polycrystalline alumina was used to investigate wet, (implying the presence of a glassy phase), and dry grain boundaries. In the first, single-crystal Al2O3 was hot-pressed via liquid phase sintering to polycrystalline alumina with an anorthite glass film at the interface. Pulsed laser deposition was used to deposit approximately 100nm-thick glass films. Specimens were annealed in air at 1650C for 20h to induce boundary migration. Boundary characterization was carried out using visible light and scanning electron microscopy. Effects on migration due to surface orientation of grains were investigated using electron back-scatter diffraction. The second method dealt with heat treating dry boundaries in polycrystalline alumina to monitor boundary migration behavior via remnant thermal grooves. Heat treatments were conducted at 1650C for 0.5h. The same region of the sample was mapped using visible light microscopy and atomic force microscopy and followed over a series of 0.5h heat treatments. Boundary migration through a pore trapped inside the grain matrix was of particular interest.

Studying Alumina Boundary Migration Using Combined Microscopy Techniques. J.L.Riesterer, J.K.Farrer, N.E.Munoz, S.R.Gilliss, N.Ravishankar, C.B.Carter: Journal of Physics - Conference Series, 2006, 26, 123-6