Fabrication of TiB₂ Particle Dispersed FeAl-based Composites by Self-propagating High-temperature Synthesis

Abstract

FeAl–TiB₂ composites have been produced from mixtures of Fe, Al, Ti and B powders using the Self-propagating High-temperature Synthesis (SHS or combustion synthesis) method. When the powder mixture was heated in vacuum to approximately 900 K, an abrupt increase in temperature was observed, indicating that the SHS reaction occurred in the powder mixture. The treating time from the start of heating to the end of the exothermic reaction was only approximately two minutes. X-ray diffraction analyses revealed that the SHS sample consisted of only FeAl and TiB₂ without any elemental metals and any other compounds. Metallographic investigations using a scanning electron microscope and an electron probe microanalysis revealed that fine TiB₂ particles were dispersed in FeAl matrix phase. As the volume fraction of the TiB₂ particles was increased from 0.3 to 0.8 by controlling the powder mixture composition, the average TiB₂ particle size increased from 1 to 7 μm and the average Vickers hardness of the composites increased from 800 to 1 600.