溶融AlへのFeワイヤー浸漬実験に基づくFeAl金属間化合物の燃焼合成における反応速度定数の推定

抄録

  The reaction rate for the formation of Fe-Al intermetallic compounds was examined by dipping experiment of Fe wire into Al melt in the temperature range between 973 K and 1373 K, to determine the kinetic parameters of combustion synthesis of FeAl. A piece of Fe wire and Al powder were put into an alumina crucible, and vacuum-sealed in a quartz tube. The tube was held in an electric furnace to promote the compound formation reaction. A microstructure observation and SEM-EDX analysis of the dipped Fe wire were performed. It was found that the compound formation reaction occurred at the interface between the molten Al and the Fe wire, and a cylindrical Fe₂Al₅ layer was formed in the wire. The thickness of the formed layer depended on the holding time and the dipping temperature. The reaction process has been similar to the combustion synthesis of FeAl intermetallic compound. Therefore, the kinetic parameters could be determined by the dipping experiment. The experimental data have been analyzed using a cylindrical model which took into account the diffusion process of Al in the Fe₂Al₅ compound layer and chemical reaction process on the interface between Fe₂Al₅ and Fe. The diffusion coefficient, D_Al and the reaction rate constant, k_c were estimated. The curves were calculated by using the obtained kinetic parameters and were in satisfactory agreement with the experimental values.
log₁₀ D_Al/m²•s⁻¹=−1887/T−8.369
log₁₀ k_c/mol•m⁻²•s⁻¹=−3177/T+1.839