Synthesis of TiB2-Al2O3-FeAl composites via self-sustaining combustion with Fe2O3/TiO2 -based thermite mixtures

摘要

A novel fabrication route combining combustion synthesis and thermite reactions was applied to prepare TiB2-Al2O3-FeAl composites with a broad composition range. The staring materials including Fe2O3, TiO2, Fe, Al, and amorphous boron powders formulated two reaction systems which were conducted in a self-propagating high-temperature synthesis (SHS) manner. Formation of xFeAl-0.6TiB(2)-Al2O3 composites with x = 2.5-3.6 and 3FeAl-yTiB(2)-Al2O3 composites with y = 0.6-1.0 was achieved through the SHS process. The increase of FeAl and TiB2 caused a decrease in reaction exothermicity, and therefore, a lower combustion propagation rate. Based upon a correlation between the measured combustion front velocity and temperature, the activation energy E-a = 90.84 kJ/mol was determined for the thermite-type SHS reaction. The thermite reduction of Fe2O3 was considered as the governing step to trigger the reaction sequence.