The Influence of Technological Parameters on the Phase Nucleation During Heating of Iron and Aluminum Powders in Isothermal Conditions

摘要

The kinetics of Fe-AI intermetallic phase transformation preceding the SHS reaction for isothermal conditions was investigated by DSC technique. Johnson-Mehl-Avrami (JMA) model was used to calculate basic kinetics parameters such as Avrami exponent, which characterise rate and the way of particular phase nucleation. Activation energy (E_a) of particular phase formation was determined by the Kissinger method. Investigations of sintered materials just before SHS reaction confirmed by SEM technique and XRD analysis shown, that not only Fe_2AI_5 phase and solid solution aluminum in iron but also high aluminum phases FeAI_2 and FeAI_3 are formed prior to the ignition of the synthesis. Performed tests have shown a strong influence of sintering process temperature on the phase transformation. In connection with occurring phase formation, the changes of microhardness were observed.