Pre-processing of hematite-doped alumina granules for Selective Laser Melting

Structure and composition evolution of alpha-Fe2O3 doped alumina granules during calcination is investigated by means of synchrotron X-ray powder diffraction. The alpha-Fe2O3 nanoparticles are added to increase the absorption of laser light, however, they also play a significant role in transition kinetics of alumina. It is shown that calcination in air leads to implementation of Fe3+ ions in corundum structure, while calcination in reducing atmosphere leads to creation of metallic iron. Moreover, it is demonstrated that for alumina granules consisting of a mixture of micron-size alpha-alumina, submicron alpha-alumina and nano-size gamma - /delta-alumina, it is possible to obtain a system composed of two corundum-type structures with different Fe doping levels and the ratio of these two phases can be controlled by calcination temperature.