Interaction Between the Growth and Dissolution of Intermetallic Compounds in the Interfacial Reaction Between Solid Iron and Liquid Aluminum

The interfacial reaction between solid steel and liquid aluminum has been widely investigated in past decades; however, some issues, such as the solid/liquid interfacial structure, formation mechanisms of FeAl₃ and Fe₂Al₅, and interaction between the growth and dissolution of intermetallic compounds, are still not fully understood. In this study, a hot-dipping method is designed to investigate the interfacial reaction in the temperature range between 973 K and 1273 K (700 °C 1000 °C) for 10 to 60 seconds. The intensification of the dissolution leads to the transformation of FeAl₃/liquid aluminum into Fe₂Al₅/liquid aluminum in the solid/liquid structure with increasing reaction temperature. The formation of FeAl₃ adhered to the interface depends not only on the reaction mechanism but also on precipitation at relatively low temperatures. In contrast, precipitation is the only formation mechanism for FeAl₃ at relatively high temperatures. Austenitizing results in the complete transformation of the tongue-like Fe₂Al₅/Fe interface to a flat shape. The growth of Fe₂Al₅ with respect to the maximum thickness is governed by the interfacial reaction process, whereas the growth of Fe₂Al₅ with respect to the average thickness is governed by the diffusion process in the range of 973 K to 1173 K (700 °C to 900 °C) for 10 to 60 seconds. The dissolution of the parent metal is due to the natural dissolution of FeAl₃ at low temperatures and Fe₂Al₅ at high temperatures.