Atomistic study of intermetallics of Fe–Al–Zn system and their interfacial properties

Abstract

Galvanizing is an important industrial process to improve the corrosion resistance of advanced high strength steels (AHSSs) that are vital for automotive industries. During galvanizing, nanoscale intermetallic phases with complex crystal structures are formed at the interface between the steel substrate and the zinc overlay. To better understand the nanoscale structures and the interfacial properties between the intermetallics, in this work, we develop a second nearest neighbor (2NN) Fe–Al–Zn ternary Modified Embedded Atom Method (MEAM) potential to describe the crystal structures of the intermetallics, i.e. Fe3Al8, Fe4Zn9 and FeZn13 and to calculate the interfacial structure and energy between them. The developed MEAM potential describes well the complex crystal structures and can be used to investigate the interfacial properties that are difficult to obtain from experiments. The Fe4Zn9, FeZn13 surface energies; the Fe–Fe4Zn9, Fe–FeZn13, Fe3Al8–FeZn13 interfacial energies; and the work of adhesion are calculated with the developed MEAM potential. The results show that FeZn13 crystal orientation has an insignificant effect on the FeZn13 surface energy and the Fe–FeZn13 interfacial energy. A negative interfacial energy is obtained for the Fe–Fe4Zn9 and the Fe–FeZn13 interface. The lowest interfacial energy is obtained in the {100}Fe case. The interfacial energy of Fe3Al8–FeZn13 depends on the surface termination of Fe3Al8 and FeZn13. A low interfacial energy is obtained when the surface termination of Fe3Al8 and FeZn13 are both Fe rich. In contrast, when the surface termination of Fe3Al8 is Al rich or the surface termination of FeZn13 is Zn rich, no low energy, stable interface can be formed between the two phases.