In-Situ observation of local atomic structure of Al-Cu-Fe quasicrystal formation.

ABSTRACT: The phase and local environment, neighbouring atoms and coordination numbers (CN), for an Al-Cu-Fe multilayer were studied during heating (to 800?°C) and cooling (to room temperature) processes using in-situ X-Ray diffraction (XRD) and in-situ X-ray absorption spectroscopy (XAS) techniques to investigate the formation of Al-Cu-Fe quasicrystals (QCs). In-situ XRD clarified the transition of the ?-Al7Cu2Fe phase to a liquid state at the high temperature which transformed into the QC phase during cooling. The in-situ XAS showed a relatively small shift in distance between Cu-Al and Fe-Al during the phase evolution from RT to 700?°C. The distance between Cu-Cu, however, showed a significant increase from ?-phase at 700?°C to the liquid state at 800?°C, and this distance was maintained after QC formation. Furthermore, the CN of Fe-Al was changed to N?=?9 during cooling. Through our observations of changes in CN, atomic distances and the atomic environment, we propose the local structural ordering of the quasicrystalline phase originated from a liquid state via ?-phase. In this study, we give a clear picture of the atomic environment from the crystalline to the quasicrystalline phase during the phase transitions, which provides a better understanding of the synthesis of functional QC nanomaterials.

SUBMITTER: Parsamehr H 

PROVIDER: S-EPMC6362143 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature