To study the formation of Al-Cu-Fe quasicrystals (QC) in the Al-Cu-Fe multilayer film, in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were used during heating (up to 800 °C) and subsequent cooling to room temperature. The phase composition, local environment, nearest atoms and coordination numbers (CN) were analyzed. In situ XRD showed that at high temperature the ω-Al7Cu2Fe phase melts, and upon cooling the QC phase is formed. In situ XAS demonstrated minor changes in the Cu-Al and Fe-Al interatomic distances during heating from room temperature to 700 °C. However, the Cu-Cu distance increases significantly upon transition from the ω-phase at 700 °C to the liquid at 800 °C, and remains large in the QC-phase. Upon cooling, the CN of Fe-Al changes to N = 9. Based on the changes in CN, atomic distances and atomic environment, it is hypothesized that the local structure of the quasi-crystalline phase is formed from the liquid phase through the ω-phase. This study provides a clear understanding of the atomic environment during the phase transition from the crystalline structure to the quasi-crystalline one, which contributes to a better understanding of the synthesis of functional QC nanomaterials.
Al-Cu-Fe quasicrystals, which possess a unique combination of aperiodic order and long-range order, have attracted considerable attention in materials science. Understanding the mechanisms of their formation is crucial for optimizing their properties. Observing the local atomic structure during the growth of quasicrystals allows us to identify the key stages and factors that control this process.
Research methods such as high-resolution transmission electron microscopy and X-ray diffraction allow the atomic structure of quasicrystals to be studied with high spatial resolution. Analysis of diffraction patterns and high-resolution images allows identification of different types of atomic clusters and their relative positions.
Studying the local atomic structure during the formation of Al-Cu-Fe quasicrystals provides valuable information on the growth and stabilization mechanisms of these complex structures. This knowledge can be used to develop new materials with improved properties.
Author: Parsamehr, H., Lu, Y.-J., Lin, T.-Y., Tsai, A.-P., Lai, K.-H.
Institute: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, 30013, Taiwan, National Synchrotron Radiation Research Center, Hsinchu, Taiwan 30076, Department of Electrical Engineering, Tokyo University of Science, Tokyo, Japan