Formation mechanism of multilayer aluminide coating on 316L stainless steel by low-temperature pack cementation

In this study, the aluminide coating was prepared by a combined process. The coating thickness and phase structure at different aluminizing temperatures and times were investigated. In addition, the thermodynamics and kinetics of the pack cementation aluminizing process were studied. The aluminizing temperature had influence on the coating phase structure. As the temperature and time increased, the coating thickened. In the process of pack cementation aluminizing, the Fe2Al5 phase was formed first, followed by the FeAl and FeAl3 phases. As the temperature was lowered to below 422 degrees C, the Fe3Al phase began to form. The kinetic study showed that the low-temperature aluminizing process had a low activation energy value of 164.78 kJ/mol. This research provided a theoretical basis for the parameter selection of low-temperature pack cementation aluminizing process.