Growth kinetics and thickness prediction of interfacial intermetallic compounds between solid steel and molten aluminum based on thermophysical simulation in a few seconds

The growth kinetics of intermetallic compounds (IMCs) generated by initial interfacial reaction (interaction time < 10 s) between solid steel and molten aluminum was investigated using a thermophysical simulation method. According to the morphology evolution of the η (Fe2Al5) and θ (Fe4Al13) phase layers in the isothermal experiments in seconds, it is confirmed that the reaction diffusion controls the η phase growth and the θ phase precipitates from the liquid phase during cooling. The growth kinetics models of the η phase maximum and average thickness are proposed as well. The results showed that the maximum growth was governed by the interfacial reaction, whereas the average thickness was governed by a diffusion and interfacial reaction process. Considering the application of the kinetics model in welding-brazing of Fe/Al dissimilar metals, a mathematical model to predict the average thickness of η phase was established using the finite difference method in thermal cycles as well. The predicted results are consistent with the experimental results, indicating that the model is of good accuracy.