Published online by Cambridge University Press: 15 February 2011
A nanoindentation study of a calcium-aluminosilicate/α-alumina system is described. Thinfilms of CaAl2Si2O8 glass were deposited on α-alumina single crystals of {1120} and {1102} orientations by pulsed-laser deposition. These samples were then subjected to a heat treatment causing the glass to crystallize and to dewet the sapphire surface. A nanoindentation device retrofitted on an atomic force microscope was employed to probe the mechanical properties of the samples. It uniquely enables the characterization of sub-micron features such as the dewet crystallites which necessitate small displacements and exact positioning of the indenter. Strong dependencies on the crystallographic anisotropy were observed in the morphology, but less so on the mechanical properties. In addition, displacement-excursions were observed and are explained in terms of yielding in the substrate.