Alumina fibers have significant potential for applications due to their high elastic modulus, and thermal and chemical stability for use as the reinforcing phase in high temperature composites. Alpha-alumina (corundum) fibers, grown by a Vapor-Liquid-Solid (VLS) deposition process, were recently produced by Neoker, based in Spain, which is a spin-out company of the University of Santiago de Compostela. In the present study the fibers were characterized in terms of size distribution, fiber surface morphology, chemical composition and planar defect content using different electron microscopy techniques (SEM, TEM, EBSD and EDS).
The fiber length was between ~1 µm and 2.5 mm, with a broad distribution. SEM micrographs revealed fibers with different morphologies, such as dendritic or faceted fibers. Growth steps at the surfaces were observed. The growth direction was analyzed by TEM, and initial analysis showed that the fiber growth direction is the C-axis direction, and the growth steps at the surface are composed of the (1 0 -1 1) and (-1 0 1 2) planes. EBSD analysis of 23 fibers showed that more than 95% of the fibers are single crystalline.
