Revealing the Epitaxial Interface between Al₁₃Fe₄ and Al₅Fe₂ Enabling Atomic Al Interdiffusion

Abstract

Steel is the most commonly manufactured material in the world. Its performances can be improved by hot-dip coating with the low weight aluminum metal. The structure of the Al∥Fe interface, which is known to contain a buffer layer made of complex intermetallic compounds such as Al5Fe2 and Al13Fe4, is crucial for the properties. On the basis of surface X-ray diffraction, combined with theoretical calculations, we derive in this work a consistent model at the atomic scale for the complex Al13Fe4(010)∥Al5Fe2(001) interface. The epitaxial relationships are found to be [130]Al5Fe2 ∥[010]Al13Fe4 and [1 1̅0]Al5Fe2 ∥[100]Al13Fe4 . Interfacial and constrained energies, as well as works of adhesion, calculated for several structural models based on density functional theory, identify the lattice mismatch and the interfacial chemical composition as main factors for the stability of the interface. Molecular dynamics simulations suggest a mechanism of Al diffusion to explain the formation of the complex Al13Fe4 and Al5Fe2 phases at the Al∥Fe interface.

Orientation Relationship of the Intergrowth Al13Fe3 and Al13Fe4 Intermetallics Determined by Single-Crystal X-ray Diffraction

“…There are also a number of works mentioning the co-existence of Al 13 Fe 4 with a pure Al matrix or another phase like Al 5 Fe 2 [49,50]. However, the orientation relationship between Al 13 Fe 4 and Al 5 Fe 2 has only very recently been reported by Chatelier et al as far as we know using surface X-ray diffraction [51]. The orientation relationship between Al 2 Fe and Al 5 Fe 2 has been studied very recently by our group [52].…”