Revisiting the crystal structure of the equilibrium S (Al2CuMg) phase in Al-Cu-Mg alloys using X-ray absorption spectroscopy (XAFS)

TL;DR

This study uses X-ray absorption spectroscopy to verify the crystal structure of the Al2CuMg phase in Al-Cu-Mg alloys, confirming the Perlitz & Westgren model as the accurate representation.

Contribution

The paper provides experimental verification of the Al2CuMg structure, resolving previous controversies by comparing multiple models with XAFS data.

Findings

PW model matches experimental XAFS spectra

Other models do not align with observations

XAFS effectively verifies crystal structures

Abstract

Even though, the crystal structure of the intermediate (S') and the equilibrium S (Al2CuMg) phase were subject of many investigations by using mostly imaging or diffraction techniques, the results remain still controversial. In this study, we used X-ray absorption spectroscopy (XAFS) to verify the correct structure considering the well-known models reported by Perlitz & Westgren (PW), Mondolfo, Radmilovic & Kilaas and Yan et al. The structure was confirmed by direct comparison to simulated XAFS spectra using the software tool FDMNES. Our results support the widely accepted PW model as the correct structure while other models do not match our observations.