Combustion synthesis of Fe₃Al/TiC composite powders

Abstract

A mixture of (FeTi₂+C)+10 at-%Al based on stoichiometry of Fe₃Al+TiC was used for a combustion front quenching test. The microstructural evolution during combustion synthesis was analysed by scanning electron microscopy and energy dispersive spectrometry. The phase constituents of the product were evaluated by X-ray diffraction. At first, Al powders were melted at 933 K and surrounded FeTi₂ particles and carbon powders. When the temperature increased to 1358 K, FeTi₂ melted, and Al and C dissolved in Fe and Ti. Then, solid–liquid and liquid–liquid reactions took place, and TiC and Fe₃Al formed. At least at 1723 K, the iron aluminide phase surrounded large TiC particles. Because of formation of TiC_0·95, a small amount of carbon remained in matrix and reacted with Fe₃Al and formed Fe₃AlC. Based on these results, the mechanism of the Fe₃Al–TiC combustion synthesis could be described with a ternary solution precipitation mechanism.

Keywords:

• X-ray diffraction
• Composites
• Intermetallics
• Self-propagating synthesis
• Phase transformation