Author: Keiichi Edagawa, Atsushi Waseda, Kaoru Kimura, H. Ino

Institute: Institute of Solid State Physics, The University of Tokyo, Roppongi, Minato-ku, Tokyo 106, Japan

Annealing of melt-pulled Al-Cu-Fe quasicrystals is a key process affecting their structural and functional properties. The effect of annealing on X-ray diffraction (XRD) peaks in these materials provides valuable information about the order and symmetry of their structure. Thermal relaxation occurs with increasing annealing temperature, which can lead to changes in the intensity and width of diffraction peaks.

The structural changes of the icosahedral phase of Al-Cu-Fe obtained by the melting method were investigated using X-ray powder diffraction after heat treatment. When annealed at temperatures above 600 °C, the width of the diffraction peaks of the icosahedral phase in the Al65Cu20Fe15 sample is significantly reduced and becomes comparable with the peak width of the standard fcc aluminum sample annealed at 820 °C. In contrast, for the Al65Cu22Fe13 sample, the peaks exhibit noticeable distortions when annealed at about 600 °C, which is due to the formation of a rhombohedral approximating crystal structure.

Experiments show that with increasing annealing time, there is a noticeable improvement in the sharpness and symmetry of the peaks, which may indicate an increase in crystallinity and improvement of the structure. The ordering of atoms in quasicrystals caused by annealing leads to the appearance of additional diffraction maxima, which also indicates the development of long-row order.

Thus, optimization of annealing parameters — temperature and time — is an important task for obtaining the desired properties of quasicrystals. This opens up new horizons for the application of these materials in various fields of science and technology, including heterogeneous catalytic processes and materials with unique mechanical properties.